Lacan07
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Ah yes, my bad! I assumed we were talking masonry. It's been a long day!Timber moisture meters are fine for timber, not so much for sticking into plastered walls
- Thread starter monica357
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No moisture meter will be perfectly calibrated for any single piece of wood, but a series of tests over weeks/months will categorically show you if it's getting wetter or dryer.
I guess the same should apply for plaster or masonry - it's just the single spot test from a 'damp-proofing professional' that's discredited
I guess the same should apply for plaster or masonry - it's just the single spot test from a 'damp-proofing professional' that's discredited
Well, over the last few days I have been monitoring things-always monitoring and losing the will to live-. The joist I showed in the pic sometimes gets almost totally dry and then attracts the damp in the same patterns if there is more moisture in the air. I really am trying to control humidity and I find the Thermo Pro hydrometer good for this. Have not used moisture meter yet-although they have been used by any 'expert' who's been. BUT, I decided to put a piece of newspaper amongst the rubbly lower hearth for a few days and have just looked at it and it is wet, not soaking, but wet. This suggests the constructional hearth is wet somewhere. This is why I thought I needed to investigate properly by having it dug and restructured as one surveyor said. I do think like you-if it ain't broke don't fix etc, but if I get the floor all sorted and coverings put down etc-wouldn't be months yet! and then have issues I'll never forgive myself. It could be because the water from my neighbour's leak has penetrated it and it hasn't dried properly yet but it could take forever!!
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Hi Monica,
What can you tell us about how the hearth is constructed? Is it a solid mass or constructed of bricks and mortar?
May be an idea to clear away all the loose debris lying on the surface and then lay a newspaper, all of it, down to repeat your test. Newspaper is so porous it will attract moisture very quickly and if the hearth is very wet the rear pages should be soaking within a few hours at most.
Cheers,
Steve
What can you tell us about how the hearth is constructed? Is it a solid mass or constructed of bricks and mortar?
May be an idea to clear away all the loose debris lying on the surface and then lay a newspaper, all of it, down to repeat your test. Newspaper is so porous it will attract moisture very quickly and if the hearth is very wet the rear pages should be soaking within a few hours at most.
Cheers,
Steve
Hi Steve,
I have attempted what you suggested leaving the paper there for a much longer time. There is no moisture on the underside at all.
The hearth is constructed I think with mortar and loose rubble rather than neat bricks. It's as if when it was constructed the Victorian builders just put a load of rubble in a pile and covered it over with a slab. This slab was crumbling so I took most of it up. It was 'painted' black. Underneath this thin slab is what looks like mortar or cement. I don't know. Here are some pics: The first two show the right and left side and the third shows the front, where there is a row of bricks.
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Hi Monica,
Well, that's good news at last as it seems that your damp problem has been solved and you should now be able to put the floor back to rights without tearing out the fireplace. It is not unusual to find that hearths are constructed of building waste and mortar, any scrapped bricks and other non combustible detritus would be chucked in there to allow the use of an open fire. There are several possibilities concerning the thin black layer of material under the decorative fire surround but its most likely a self-levelling floor compound that was installed before the more modern fireplace/surround was installed. You will need to think through how you intend to proceed after re-fitting the floorboards. Let us know if you have any concerns regarding how to proceed.
Cheeres,
Steve
Well, that's good news at last as it seems that your damp problem has been solved and you should now be able to put the floor back to rights without tearing out the fireplace. It is not unusual to find that hearths are constructed of building waste and mortar, any scrapped bricks and other non combustible detritus would be chucked in there to allow the use of an open fire. There are several possibilities concerning the thin black layer of material under the decorative fire surround but its most likely a self-levelling floor compound that was installed before the more modern fireplace/surround was installed. You will need to think through how you intend to proceed after re-fitting the floorboards. Let us know if you have any concerns regarding how to proceed.
Cheeres,
Steve
Hi Steve, Thanks for this, but the thing is if I put my hand in any gap amongst the rubbly underpart there is slight damp-eg I can manage this in a gap shown in the second pic. Also I think I can remember there were red tiles under that fire surround before it was installed-possibly part of the original fireplace that must have been there long before my time. I don't think they were taken up and they are porous aren't they? Those joists still dampen up when humidity is high as in last few days which I worry about but will eventually have them replaced I think- treated ones won't have this problem I feel.
But....I have noticed another issue now which you may have some thoughts on. Now that I have become obsessed with damp!!!! I lifted up a few more boards on the opposite side of the room , window side. Now I had that wall stripped back and re rendered and plastered October 2021 and had a french drain installed outside . When I lifted the boards in one corner I noticed wet on the underfloor surface. I think it's rainwater seeping in somehow. I amateurishly attempted to dry it out with a hairdryer only for an hour though-and it definitely started to dry, but got wet again when the rains came yesterday. I am now wondering if the builders who installed the drain did a botch job. I have contacted the surveyor who recommended the work but doubt if he'll get back to me. There is no issue I can see outside and gutters look ok, but that water is coming from somewhere. Any thoughts on this new concern? Also I want to say you've been really helpful so far-at least I feel I can discuss these issues with someone who has the knowledge. Not sure I'm ready to refit floorboards yet.
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Hi Monica,
Your hearth was undoubtedly built directly over the earth and has no damp course per se. Consequently it will continue to absorb moisture from the ground and, while much of the excess water absorbed from the leaks you have had has now evaporated off it will never be genuinely bone dry. This is entirely natural and to be expected with older houses and is managed through the use of breathable materials in ints original construction and future maintenance. Given the various proofs of your success in remedying the leaks and driving out excess moisture I think that it is safe to start getting the house back in order and re-laying the floors.
Theres no need to worry about any old tiles that may have been left in the hearth. They will behave just like any other building waste in its structure and will do no harm. You need not be concerned by the timbers feeling a little damp at times, the wood is much more porous than other materials and will leach moisture from the atmosphere whenever humidity in the room is high. This too is part of the natural breathing of the building and can be considered a healthy sign.
Regarding your new concerns. Some photos may be helpful understanding what may now be going on.
Cheers,
Steve
Your hearth was undoubtedly built directly over the earth and has no damp course per se. Consequently it will continue to absorb moisture from the ground and, while much of the excess water absorbed from the leaks you have had has now evaporated off it will never be genuinely bone dry. This is entirely natural and to be expected with older houses and is managed through the use of breathable materials in ints original construction and future maintenance. Given the various proofs of your success in remedying the leaks and driving out excess moisture I think that it is safe to start getting the house back in order and re-laying the floors.
Theres no need to worry about any old tiles that may have been left in the hearth. They will behave just like any other building waste in its structure and will do no harm. You need not be concerned by the timbers feeling a little damp at times, the wood is much more porous than other materials and will leach moisture from the atmosphere whenever humidity in the room is high. This too is part of the natural breathing of the building and can be considered a healthy sign.
Regarding your new concerns. Some photos may be helpful understanding what may now be going on.
Cheers,
Steve
Hi Steve,
I attach some poor photos. Problem is the joist is in the way and I have had to use a torch to get light there but you can just see the darker water stains in front and behind the joist.
I mentioned before I contacted the surveyor who recommended a french drain outside last year and he did get back to me. He asked me to dig out shingle to see if there was concrete or soil underneath. It looked like concrete so he said they didn't dig down far enough as it should be soil at the bottom but if so why isn't water coming in all along inside, not just this corner. I'll dig down again when the weather is dryer to check how far below the slate damp proof course they dug-should be 150mm I think.
There are two pipes coming down from ceiling to floor in that corner but they are not leaking and not near enough to the ingress. They are water pipes for the c. heating. Be good to read your thoughts on this problem.
Can't believe just over a year ago this room was lovely except for dodgy plaster in places, now it's like a building site, but it's best I know what's going on before moving forward with cosmetics!
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Hi Monica,
There are a number of possibilities but if there is concrete under the drain its likely that water is pooling in that immediate area on top of the concrete and soaking through the wall. It may also be due to the builders failure to ensure an adequate 'fall' of water in the drain toward the exit point(s). The drain itself should be sited below the level of DPC. Its a bit late in the year to do anything about this as you may need to excavate the whole drain to ensure that it is aligned properly, at the right height, has an appropriate fall and that water is escaping from it only at the correct locations.
Cheers,
Steve
There are a number of possibilities but if there is concrete under the drain its likely that water is pooling in that immediate area on top of the concrete and soaking through the wall. It may also be due to the builders failure to ensure an adequate 'fall' of water in the drain toward the exit point(s). The drain itself should be sited below the level of DPC. Its a bit late in the year to do anything about this as you may need to excavate the whole drain to ensure that it is aligned properly, at the right height, has an appropriate fall and that water is escaping from it only at the correct locations.
Cheers,
Steve
Hi Steve, Checked again yesterday. There is a light browny clay under the pebbles, soft, and no pool of water, just a bit soggy. We've had a fair bit of rain here lately. I was looking for the usual dark brown soil which is why I thought this was concrete at first. I used a metal spike to push into it and it went through easily. The bottom is approx. 150mm below the slate damp proof course so all of that seems right don't you think. Not sure what you mean about fall-they did what the surveyor said-dug the trench 150mm below slate damp proof course and then filled it with the pebbles!!!! By fall do you mean the angle of the trench? Angles weren't mentioned-the idea was that water would soak into the soil beneath.
I have also been testing around the fireplace some more. I put some newspaper down like before-it's just damp after a week, but in the first pic you can see wet on the joist edge-this is a sooty wetness to the touch!
This suggests that the wetness there in the first place, as shown in the second pic, when I first discovered it, (note there is brown paper on top of the area which was under the carpet) is still there when humidity is high. Underneath the concrete base is also still wet after a year!. This could have something to do with my neighbour's leak. If water got under the concrete of that constructional hearth the industrial dryers wouldn't have been able to reach it, not in the short time they were here.
I really think the base in front of the fireplace will need to be relayed or get rid of the whole foreplace and get a new one. I definitely think it's best to replace the wet joist to the right of the fireplace which I mentioned before as it's the only one which attracts humidity-it looks sound enough but has those wretched patterns of wetness. I need to have debris removed from the subfloor anyway. I have managed a lot myself but can't reach it all. Other joists all seem dry but may have had a woodworm problem years ago so maybe replace some of these too. My main worry is finding a builder who really knows their stuff in these areas, but that will have to be for later on. There's a lot here-my brain is frazzled! I hope yours won't be.
I have also been testing around the fireplace some more. I put some newspaper down like before-it's just damp after a week, but in the first pic you can see wet on the joist edge-this is a sooty wetness to the touch!
This suggests that the wetness there in the first place, as shown in the second pic, when I first discovered it, (note there is brown paper on top of the area which was under the carpet) is still there when humidity is high. Underneath the concrete base is also still wet after a year!. This could have something to do with my neighbour's leak. If water got under the concrete of that constructional hearth the industrial dryers wouldn't have been able to reach it, not in the short time they were here.
I really think the base in front of the fireplace will need to be relayed or get rid of the whole foreplace and get a new one. I definitely think it's best to replace the wet joist to the right of the fireplace which I mentioned before as it's the only one which attracts humidity-it looks sound enough but has those wretched patterns of wetness. I need to have debris removed from the subfloor anyway. I have managed a lot myself but can't reach it all. Other joists all seem dry but may have had a woodworm problem years ago so maybe replace some of these too. My main worry is finding a builder who really knows their stuff in these areas, but that will have to be for later on. There's a lot here-my brain is frazzled! I hope yours won't be.
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Hi Monica,
Sorry for confusing you, 'fall' refers to the slope needed in a drain/pipe to ensure that water flows in the right direction toward an exit or soak-away. Given the mass of that hearth, and added to the fact that its set directly on the earth below, it could take years to thoroughly dry out. Particularly if the local water table is high or during/after long periods of heavy rain. Frankly its a tough call to make as to whether the hearth and fireplace should be completely removed and to some extent it must be based on what makes you feel most comfortable. Should you decide to do so, it may be possible to remove the fireplace without damaging it and re-install it later should you choose to keep it.
Bluntly, I'm impressed by your patience, mine would have been exhausted long ago and I would probably have taken drastic measures sooner - but then I'm not known for my forbearance. Don't be too quick to replace the joists though if they are showing good signs of drying out and there's no softness or collapse of the fibres present. A good woodworm killer/inhibitor treatment may be all that's needed.
Sorry I can't be of more help than this.
Cheers,
Steve
Sorry for confusing you, 'fall' refers to the slope needed in a drain/pipe to ensure that water flows in the right direction toward an exit or soak-away. Given the mass of that hearth, and added to the fact that its set directly on the earth below, it could take years to thoroughly dry out. Particularly if the local water table is high or during/after long periods of heavy rain. Frankly its a tough call to make as to whether the hearth and fireplace should be completely removed and to some extent it must be based on what makes you feel most comfortable. Should you decide to do so, it may be possible to remove the fireplace without damaging it and re-install it later should you choose to keep it.
Bluntly, I'm impressed by your patience, mine would have been exhausted long ago and I would probably have taken drastic measures sooner - but then I'm not known for my forbearance. Don't be too quick to replace the joists though if they are showing good signs of drying out and there's no softness or collapse of the fibres present. A good woodworm killer/inhibitor treatment may be all that's needed.
Sorry I can't be of more help than this.
Cheers,
Steve
Bit left field and more than happy to be shouted down by more experienced members of this parish, but would it be worth considering installing some DPC membrane vertically between the constructional hearth and the joists/floorboards? It could still breathe and dry vertically but would prevent the progress of damp / moisture horizontally into joists and flooring.
Alternatively if you are getting thoroughly bored by the situation then yes, replace salt damaged joist and re-do hearth and then get on with life
Alternatively if you are getting thoroughly bored by the situation then yes, replace salt damaged joist and re-do hearth and then get on with life
Lacan07
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Are you talking about the ground / earth beneath your suspended floor? And when you say wet, how wet? Its not uncommon for the ground to get damp, especially after extended periods of rain fall.
Hi, Thanks for taking the time to contribute to the conversation about my dilemmas. It's the ground/ earth-what the property is built on. There's no earth there, just ground. The corner is I'd say wet. It's not pouring in-we had loads of rain last night and this morning-but nevertheless seeping in. I have a small extension next to that part of the french drain and am wondering if it's under that where the problem is. God knows how I'll fix that.
Well Steve, you have been loads of help so far. Please don't give up on me. Having looked at some of the issues some of the other contributors are having , mine all seems pretty small fry!!! But...I'm a bit of a slow and steady person and trying not to lose my grip. I would like to know what the 'drastic' measures you would have taken are though. Regarding the joists- they are solid. I pressed a screwdriver to them the other day and it wouldn't go through, so maybe a treatment would be enough. They are bone dry in places-the damp parts form a pattern. The only reason I thought it best to replace rather than treat was because I thought new treated wood would resolve the intermittant damp issue completely whatever the humidity.
As for the fireplace. Well I was told that it would have to be broken up to remove as it's solid stone and glued to the wall rather than fixed with brackets. There is a void under the constructional hearth on one side, enough to get my hand in and it is wet. The insurance who sent the industrial drying company round said I could contact them direct to ask if they can come out and maybe target the drying equipment to that area specifically rather than go down the 'natural' route. What do you think? The strange thing is the carpets and underlay over the hearth were bone dry when I took them up a year ago and they had been there since 2004-it was just the brown paper beneath that was wet. So, maybe it's just something that's there for ever. The new plaster on the walls appears dry after a year which is good and therefore not affected. To be honest I'm not convinced anything is getting worse. There's a lot of soot falling down chimney though. Should I be concerned about that?
As for the french drain-well they just dug the trench and filled it with the pebbles. The surveyor didn't mention slopes and falls or pipes, so it sounds as if that's been a bad job, but it's to do with outside it seems.
Still waiting for Peter Ward's new book to come out. It's tempting to call him out but £1000 for a visit is a lot isn't it. Do you know any good London builders who I could contact?
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Hello Monica,
No I won't give up. Retreat is not a word found in my personal lexicon and certainly not an aspect of my behaviours. However, I do come from a family of engineers and bargees from whom the guidance was always 'If at first you don't succeed, hit with a hammer!' The use of such blunt instruments to vent my frustrations typically results in lots of wreckage, a bruised ego and likely broken thumbs (yes, both and I'm not ambidextrous before you ask). In truth I had not considered what 'drastic' action I would take in the circumstance so suffice it to say merely that little may be recognisable after I'd finished. Setting all that aside: -
Steve
No I won't give up. Retreat is not a word found in my personal lexicon and certainly not an aspect of my behaviours. However, I do come from a family of engineers and bargees from whom the guidance was always 'If at first you don't succeed, hit with a hammer!' The use of such blunt instruments to vent my frustrations typically results in lots of wreckage, a bruised ego and likely broken thumbs (yes, both and I'm not ambidextrous before you ask). In truth I had not considered what 'drastic' action I would take in the circumstance so suffice it to say merely that little may be recognisable after I'd finished. Setting all that aside: -
- The French Drain
- A gravel filled trench can work as an excellent drain provided the water has a route to an exit from the site. As a rule the bottom of the trench will be sloped (given a fall) toward that point of exit if it is at all possible. However, the exit point Must be lower than the bottom of the trench for it to have any chance of working effectively. It may pay you to take a look if you can at where the French drain is intended to empty out to see if the outlet, such as it may be, is lower than the highest part of the trench. If it is not then water is simply sitting in the bottom of the trench and is likely soaking through the walls of the house.
- The Joists
- It could be that the stains you're seeing are just the residue left behind when the wood was soaked. If you have a moisture metre you can take readings over a period of time to establish how wet they may be in areas of concern and whether there is a positive trend to confirm that they are drying out properly. A cheap moisture metre would cost about a tenner.
- To test whether the wood has decayed due persistent wet/damp a good test is to try to press a sharp instrument, not a screw-driver, like the needle of a school compass or meat skewer into a few spots in the ares of concern. If the wood is sound you should not be able to push there point in more than a couple of millimetres - unless you're a body-builder.
- Assuming the timber is dry to the touch then it can, and should, be treated with an anti-woodworm/wood preservative, to prevent future infestation.
- The Fireplace
- Everything depends on what you decide to do regarding the damp in/around the hearth. However, it may be possible to save it should the old hearth finally be removed. How to do that can be left until you decide what the best overall approach may be.
- The Hearth Void and Observed Wetness
- Depending on how severe the original leaks next door were and how long it was before they were discovered and repaired a huge amount of water may have been absorbed into the hearth and the ground below. The only escape routes for that water will have been either by spreading out through the earth to the outer walls or through evaporation through the atmosphere of the room concerned. Given where we are in the year, how wet the weather has been and the possibility that water trapped against the exterior walls may be finding its way indoors, then what you are finding in the void may simply be the result of that new water finding its way along lines of least resistance.
- Its something to keep an eye on but unless you can find a specific source of water entering this void its likely that it will be something that will cure itself when the hearth and the ground below it throughly dry out.
- Dry Carpet and Wet Paper
- As its possible that the underside of the underlay and/or the carpet may have been impermeable to water its entirely feasible that the paper got wet from contact with the floor-boards.
- Falls of Soot
- Are common at this time of year and if you have not already done so and intend to have open fires or woodturners say then I would urge you to get the chimney swept at least once a year.
- Oftentimes such falls are the result of soot trapped in the chimney getting wet and becoming too heavy to maintain its grip on the walls of the chimney. Thats normal and its unlikely to be the source of the damp you are observing below.
- Peter Ward
- He's an excellent bloke and his advice is always valuable. £1000 for an initial consultation that may lead to either peace of mind or a much bigger bill but only you can judge if that would be a good investment.
Steve
Hi Steve, I am so pleased you have replied. For a while there I thought you said all you could say and had enough! This mail gives me plenty to think about and act on. Just a quickie for the moment. I told you I contacted the original surveyor who recommended the french drain. When I told him that underneath all the shingle there was clay and water was not pooling at the bottom, he suggested this: 'an impervious material such as flat Slate roof tiles can be fixed to the surface walls and again the channel back-filled to support them which will certainly stop water migration through the wall'. What do you make of this? And by the way, there isn't an exit point except the clay underneath the shingle. Monica
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Hi Monica,
In my opinion, others may differ, a slate barrrier would merely slow the rate at which water is absorbed through the brick-work. Far better in my view to ensure that water is not allowed to accumulate in the shingle drain next to the house. The best way to achieve this is to ensure that there is a route to either lower ground away from the house or better still to a suitable waste water drain. However, if it is not viable to establish such a route then a slate barrier may reduce the water penetration to an acceptable level.
Cheers,
Steve
In my opinion, others may differ, a slate barrrier would merely slow the rate at which water is absorbed through the brick-work. Far better in my view to ensure that water is not allowed to accumulate in the shingle drain next to the house. The best way to achieve this is to ensure that there is a route to either lower ground away from the house or better still to a suitable waste water drain. However, if it is not viable to establish such a route then a slate barrier may reduce the water penetration to an acceptable level.
Cheers,
Steve
Hi Steve,
I thought his suggestion was a bit iffy. I think the surveyor was a bit iffy too now-one of the PCA? ones. I think I may need to get a french drain person in to look at how this was done. The builders just dug the trench along the wall outside that room at the surveyor's recommendation. I reluctantly chose this instead of lowering all the ground outside as that was a massive job, but once it was done I thought it looked ok. This can't be done til the weather improves though. I think I should concentrate on the fireplace issue first and put up with this.