Is it lime or modern cement?

[foppish]

*newbie alert*

the pointing.... how do I tell? I've searched through here, and googled, I've done a vinegar test - and everything blooming fizzes - even stuff I know is modern concrete.

1897 victorian semi - back and side elevations covered in render to the floor, concrete patio base flush to base of the back half of the house, cracked, internal damp problems at the base of interior walls that adjoin this and some suggestion of bounce in the suspended floor near here that might indicate floor joist rotting

this has been ongoing for years, but I noticed the plaster (modern) internally at one point was much worse than it usually is at this point in the year (it's been wet in wales this summer). We've 74% RH @ 18deg C :shock: which is dreadful for the summer. So with the winter to come, I've taken the internal plaster off to find sodden bricks and am removing the concrete patio base and the bottom of the external render to try and get some evaporation going - not the best time of year to start but needs must.

The render is coming off easily in parts and less so in others. It all looks very heterogeneous, and has obviously been messed about with numerous times. I have some lime mortar coming from ty mawr to point the brickwork, but what should I rake out? some of it is now just earth so will go, but the remainder, how do I tell what's to go and what's to stay OR at this point in the year am I just looking to sure up the in situ pointing and look at it all properly next year?

first picrures so hope this works (if not - the url's are underneath, and I've tried attaching them....)

https://www.dropbox.com/s/iubez1cp32muc2r/20151003_090118.jpg?dl=0

https://www.dropbox.com/s/a66tuf29kzjozan/20151003_090136.jpg?dl=0

https://www.dropbox.com/s/ygqzxsv4o0ukjhy/20151003_090151.jpg?dl=0

and should I be going higher up than 2 bricks, removing the render? the base render is very obviously modern concrete, but above it is softer, urggghhhh, is it just wishful thinking that the rest might be at least in part lime render?


I will try and reverse the slope that dumps all of the water from the patio and the rain fall from the front of the roof via a bizzare guttering arrangement onto the base of this corner, so that it isn't having to cope with all that, but won't be installing any french drains or anything this winter as the floor level is fine, and I need to see how the house copes with what I'm doing to the walls. Should I be doing anything else (I have poked through the airbricks, and at some stage will want to install more round the side and clear the suspended floor of debris - but that's for summer).

 

[MatthewC]

Hi foppish. Good detailed post and nice photos. Good holes in bricks - chemical DPC?

Firstly, in my experience, cement mortar is usually pretty obvious due to its brittleness whereas lime in a damp place is more likely to be soft and can be crumbled between your fingers. Also, when you break cement (with a hammer and chisel if needed), you get sharper fractures than with lime. I cannot explain your vinegar test!

Secondly, it sounds as though you've got the idea about dampness and excess water, so carry on with getting rid of the water that doesn't need to flow there. Rather than remove all the concrete patio, for now you could just remove a 6"-12" strip adjoining the wall and leave it empty for a few inches down for the winter.

Thirdly, you say "the floor levels are fine" and I can see steps up from the ground - how much higher is the floor level? Is it all a wooden suspended floor? You could think of fitting a vent in the floor on the side opposite to the external wall.

Finally, you also seem to have the idea about removing modern plaster and cement, and then just letting it dry out. However, you might need to remove more render as you say you have damp walls on the inside. Currently you have only removed external render up to the floor level so any damp in the wall a foot or more above the floor can only go down (slowly) or inside, can't it? I'm not even sure I'd bother to do pointing now unless it really is very bad - I had huge holes on my house at the base of the walls where an ignored broken downpipe had caused the mortar to be washed away over a period of years; I did the downpipe but didn't get round to fixing the pointing for a year or more!

Best of luck - stick with it as it all happens very slowly!

Matthew

 

[Lime]

From what I can see it is all lime mortar between the bricks except the whitish line under the doorstep, that looks like a cement/lime mix to me.

I'd rake out the mud, wash it out with a hose if necessary, and point up with lime.

 

[foppish]

thanks people, very much appreciated - whilst not a grand property, and a relative baby, it is our home, I love it and don't want it to fall down! (some of the properties being rennovated on threads here are amazing)

I *think* the reason the cement was fizzing is that it was covered in crumbled soft lime mortar powder.

I've created a channel by the wall - removing the cement as suggested. I may pop some pond liner down to form an actual channel rather than a soak onto the footings (if I have footings :? )

I've taken off the render for 4 bricks up, and found missing bricks (well - not found missing bricks - found holes where bricks should be....), a soaked piece of wood instead of mortar, render made of sand only (presumably was a lime? render) all held in place by a covering of plastic paint and I could flip the sheet of render that remains between the 2 doors off the wall in one go with a plastic spatula, should I so desire.

the wall is sopping wet

and we're set for a wet welsh winter so not sure whether my next move should be to take the lot down or keep it there over winter. It's going to be lime-rendered in spring by brother but he can't fit it in until then.

 

[MatthewC]

I've created a channel by the wall - removing the cement as suggested. I may pop some pond liner down to form an actual channel rather than a soak onto the footings (if I have footings :? ).

Sounds like the start of a French drain, if you have somewhere to remove the water to!

the wall is sopping wet

and we're set for a wet welsh winter so not sure whether my next move should be to take the lot down or keep it there over winter. It's going to be lime-rendered in spring by brother but he can't fit it in until then.

In my experience the air will be a benefit even over the winter - my house dried hugely between the roof membrane going on at the end of October and the beginning of March.. Then the drying continued for another year or so!

 

[foppish]

thank you! - a lot of the render has been on the floor since about 2 mins after writing my last post to reveal not-the-prettiest american bond brickwork, but even over the course of a few drizzly days some of the more crumbly bricks seem to have stabilised and the surface is drier than it was when the render was there, as is the inside of the house. I have to admit to feeling a little apprehensive about the winter, despite reading the theories of moisture balance in solid wall houses and understanding it intellectually, it does feel slightly "wrong" to be unveiling the bricks before the hard rain hits.

However, de-rendering is quite addictive, i found myself "just tapping that next bit" and before I knew it square meters had been done. Grey lime mortar is here (which is what the fronts of the house are done with), however the back is natural/yellowy buff so am waiting for that to be delivered tomorrow and will start putting the odd missing brick back in and attending to the pointing where necessary.

 

[King of the Monkeys]

One of the biggest problems with a solid wall construction house is the trapping of moisture. This is very easy to remedy, you must remove the impermeable coatings from the outside walls. Perhaps as an interim to a dado height, which could be left to breathe.

lower the ground level outside as low as possible with out undermining the foundations , and / or create a French drain.