Exterior ground levels - and pavement issues

[BlueTed]

Morning All. I’ve been reading all of your excellent posts for some time, and this is my first post. I’m restoring an 18th century property that has had very little done to it in its life. Most things were just covered up - including an attic floor with three rooms!
I’m focussing on the exterior and the internal damp first of all. Removing some later fireplaces, which actually were multiple fireplaces built into two inglenooks has dried some internal walls out already.
The exterior ground levels are too high and I will shortly remove these. I’m not yet sure if there is a damp course or not, and what level I should be moving the ground too. Eventually I will put gravel all around the exterior of the house and not just a trench. I’m a little overwhelmed by the number of suggestions and would be grateful to understand if I don’t have DPC, is there a certain depth to dig to? If I do have a DPC I will remove everything that is breaching this, but until I start digging the higher level away I’m not sure if there is DPC or not,.
Part of my property is next to a public footpath. The tarmac surface is directly against my property and it is built 50% over the air bricks, but the floors were changed to concrete in the 70’s (presumably because they rotted due to the 60’s tarmac pavement!). The council won’t do anything despite clearly breaching the base of my property by building their pavement against it and increasing the height of the damp that is able to get in. Excuses have ranged from the pavement being there for too long (so they won’t accept they caused any issues if previous owners didn’t raise this) to my internal wall finishes are probably causing issues (despite them being timber panelling and lime plaster, and the council has never seen inside). One thing that did seem to be the genuine concern of the council is I was told in an off the cuff comment that they won’t deal with this or otherwise hundreds or thousands of property owners would come forward and make the same claims and they can’t afford to rectify these issues. Does anybody have any experience of this latter issue? It seems that because the council own the path they are the only ones who can remedy this - I don’t own it so I cannot dig it up myself, but the council are refusing to accept any responsibility. Any help and possible ways forward will be greatly appreciated!

 

[Sam W]

We have a similar issue. Our house is a former railway station, but the line that runs past is still active. At some point since the house was built (1860) the platform level has been raised, external ground level on that side of the house is now about 20cm higher than the internal floor level. Although I generally find Network Rail pretty helpful when I have to deal with them, I'm not expecting to ever get them to dig a French drain or similar, so I've focussed on mitigation.
As far as I can tell the house was built without ventilation for the sub-floor void, there's no evidence of air bricks having been fitted and damp was an issue, with some joist ends rotted away. I've now added air bricks, on the platform side of the house this meant starting above external ground level and angling the hole in the wall down so internally it's below the floor boards. This has been effective, damp is still a bit of an issue, but only at the joist ends rather than along their whole length. The musty smell that used to appear in rooms if the windows hadn't been open has gone, and the carpet is no longer damp.
I'm keen to stay on good terms with Network Rail as I rely on them for permission for things like erecting scaffolding for roof repairs, and I'm not going to hassle them about the platform height (although I am trying to get the existing surface water drains fixed, or at least get permission to do it myself). I suspect there is a route to getting the council to do something about the footpath at your house, although they will put lots of obstacles in your way. If informal conversation has come to a dead end, a professional (surveyor/structural engineer) report confirming the damage that has been done and likely consequences of not addressing the cause would be a practical next step.

 

[Feltwell]

Our house is a former railway station, but the line that runs past is still active.

Which station are you at Sam? Just curious, as a fellow Salopian!

 

[Feltwell]

Re councils and pavements -

Councils will be risk averse as ever, even mentioning liability will get them on the defensive! You *can* dig up their pavements with permission though - you can't do it yourself, but if you employ a registered contractor from their list, who has the right insurance, and let their inspector take a look then it is possible. We had our drop kerb extended by doing this.

So, whilst I'm sure it would be awkward to get permission for, putting some sort of drain alongside your wall is in theory possible, so long as the council are happy it's safe for pedestrians and won't cause them any problems. As ever it will depend on the Council though.

I had some dealings on behalf of a charity with Severn Trent Water a while back, the charity wanted to put a permanent building up - to replace a Portacabin - on land leased from Severn Trent. They wouldn't sell us the land, in case they ever needed to expand the adjacent water works, but they were happy to give a 100 year lease at a fixed rent of £1 per year, as it was a charity. They were very good in fact. Sometimes dealing with organisations can be good!

 

[BlueTed]

Thanks for your replies - seems like this will be an uphill battle, but one I have no choice but to proceed with!

 

[malcolm]

I wouldn't focus too much on the damp proof course. It wasn't the primary method in stopping damp in old houses.

Ideally the exterior ground level should be a couple of bricks (6 inches) lower than the interior floor level. If the exterior ground level is higher than the interior floor level it will lead to problems. For the difference in interior and exterior ground level to be of use in reducing damp it's important that the exterior of the wall is breathable - ie no cement pointing or render or plastic paint.

Always worth posting photos. They make it easier for others to get a practical idea of where you are rather than suggest theories that might help.

 

[BlueTed]

I wouldn't focus too much on the damp proof course. It wasn't the primary method in stopping damp in old houses.

Ideally the exterior ground level should be a couple of bricks (6 inches) lower than the interior floor level. If the exterior ground level is higher than the interior floor level it will lead to problems. For the difference in interior and exterior ground level to be of use in reducing damp it's important that the exterior of the wall is breathable - ie no cement pointing or render or plastic paint.

Always worth posting photos. They make it easier for others to get a practical idea of where you are rather than suggest theories that might help.

Thank you Malcom, really great advice. The exterior level is higher around most of my property (which I own so can have rectified) but it is the pavement part causing the issue. Thanks again!

 

[BlueTed]

I wouldn't focus too much on the damp proof course. It wasn't the primary method in stopping damp in old houses.

Ideally the exterior ground level should be a couple of bricks (6 inches) lower than the interior floor level. If the exterior ground level is higher than the interior floor level it will lead to problems. For the difference in interior and exterior ground level to be of use in reducing damp it's important that the exterior of the wall is breathable - ie no cement pointing or render or plastic paint.

Always worth posting photos. They make it easier for others to get a practical idea of where you are rather than suggest theories that might help.

Hi Malcom, I’m hoping you can offer some further advice. I will be having the render removed and the plastic paint from the brick removed in the spring (I think the company is using the Doff system to remove the paint).
I would like to dig a trench in the mean time to reduce the exterior ground level which is slightly higher than the inside. The attached image gives an idea of years of concrete and tarmac built up outside. Eventually the whole of the driveway tarmac will be removed to bring the whole level down to the correct level.
If I dig a trench, will this help in the interim, or will this cause more problems be creating a trench for water to sit in?
An idea I had, as a layman I might add, is to dig the trench to get to the correct exterior level and leave the base of the walls exposed so they’re not preventing any breathability. A layer of gravel seems to be recommended in some places to prevent as much splash back.
Is this correct?
One thing that concerns me before the whole driveway is removed is creating a moat with nowhere for the water to go. If I dig a trench that is slightly angled away from the house, would this help move water away directly from the foundations?
Many thanks.

 

[Cubist]

Almost whenever it may have been built your house would have been provided with some means for surface water to drain away. As a rule this would have been accomplished by sloping the land in an appropriate direction and ensuring that ground levels were below the damp course if installed. Check the general slop of your plot to determine the likely directions and paths of flow and make sure that any channels you may dig beside the house follow those lines wherever possible. Sometimes surface water waste was channeled to common waste and sewage pipes used for all the surrounding properties. Check for any access points in and outside your boundaries and check that any drains on your property are working properly.

 

[malcolm]

That sounds like a very similar situation to mine so I'll offer my thread: https://www.periodproperty.co.uk/forum/threads/exterior-ground-level-decision.14273/ I decided it would be too expensive to do big groundworks like lowering the driveway.

You could dig a trench temporarily. I don't believe in gravel. It might reduce splashing but if you lift up the top couple of inches it'll be soaking wet underneath. If you have an unfilled trench you might get a puddle 6 inches lower but the wall will be dry where the gravel would have been.

The photo is interesting. Are you sure all the pavement is council property? Where you have a set back from the wall the lines of responsibility can get confused. It doesn't look like the council thought it was their responsibility when they last relayed the pavement. I think adding a trench there would be fair game without permission so long as you make it really safe. Asking permission will tend to lead to having to use approved contactors who tend to charge £1000/hour.

 

[malcolm]

Though I wouldn't bother doing anything temporary for the sake of a few months. It's been like that since all the bad things were done and a few months won't make any difference.

Doff sounds good if they have painted your bricks.

 

[BlueTed]

Almost whenever it may have been built your house would have been provided with some means for surface water to drain away. As a rule this would have been accomplished by sloping the land in an appropriate direction and ensuring that ground levels were below the damp course if installed. Check the general slop of your plot to determine the likely directions and paths of flow and make sure that any channels you may dig beside the house follow those lines wherever possible. Sometimes surface water waste was channeled to common waste and sewage pipes used for all the surrounding properties. Check for any access points in and outside your boundaries and check that any drains on your property are working properly.

Thank you very much - some great advice. I believe the ground level slows down the side of the house and it’s been made ‘level’ over the years with concrete and tarmac…

 

[BlueTed]

That sounds like a very similar situation to mine so I'll offer my thread: https://www.periodproperty.co.uk/forum/threads/exterior-ground-level-decision.14273/ I decided it would be too expensive to do big groundworks like lowering the driveway.

You could dig a trench temporarily. I don't believe in gravel. It might reduce splashing but if you lift up the top couple of inches it'll be soaking wet underneath. If you have an unfilled trench you might get a puddle 6 inches lower but the wall will be dry where the gravel would have been.

The photo is interesting. Are you sure all the pavement is council property? Where you have a set back from the wall the lines of responsibility can get confused. It doesn't look like the council thought it was their responsibility when they last relayed the pavement. I think adding a trench there would be fair game without permission so long as you make it really safe. Asking permission will tend to lead to having to use approved contactors who tend to charge £1000/hour.

A very interesting post and thanks for sharing.
I was hoping to be able to do something before the spring (partly to help keep costs down, and partly my sanity of knowing about the problem and not doing anything about it!) so I’ll have a think about this, and speak to the builder.
The total works are going to cost around £50k (including 5 new windows) so I want to do what I can do, but leave the rest to the professionals. I have found a good heritage builder who does not believe in cement or modern fixes for old buildings and does everything how it would have been done.
Apologies for confusing things - the photograph shows the mismatched sideway/drive of the house, and the council owned pavement abuts the front elevation (out of view).

 

[BlueTed]

This is the councils pavement - built half way over a number of air bricks….

 

[BlueTed]

And this is their solution!!

 

[Cubist]

In the words of the immortal Leslie Philips - "Oooooh Narstie".

 

[BlueTed]

I thought I would update you all because I decided to start reducing the exterior ground level before the other works start in the spring. There was multiple surfaces, tarmac and two types of concrete below that. I got down to the original brick surface, and some flits set into the ground, and gravel. I found a great stone tablet dated 1809, and a marble flag which is likely to be medieval and from the old church which was mostly demolished in the mid-19th century. Hopefully this will help start the house breathing!

 

[BlueTed]

Is anybody able to confirm if the brick that extends out slightly at the base (about half a brick) part of the foundations? It took some time to work out what the original ground level was. When I got to the flint and gravel levels, an inch or so below this I found the slightly extended brick. I’m assuming this is supposed to be covered over as surely it would get damaged otherwise?
Apologies if this is a silly question. I’m passionate about old buildings and I will only attempt things I know I can do (such as digging a trench!) but I’m not experienced in knowing how buildings and foundations were built

 

[Cubist]

There are others here my knowledgable than I regarding the design of brick foundations but I think they would agree with me that the projecting bricks you have found are part of the foundation. These, together with others laid beside them form the level plinth or base upon which the walls are constructed. Typically the plinth is sited below ground level and, if a damp course is installed, it will be found a couple of courses above the plinth/base. If you can find no evidence of a damp course it would be wise to assume that it would usually be sited at the same level as the foot/bottom of the air-bricks you have already discovered.

 

[BlueTed]

There are others here my knowledgable than I regarding the design of brick foundations but I think they would agree with me that the projecting bricks you have found are part of the foundation. These, together with others laid beside them form the level plinth or base upon which the walls are constructed. Typically the plinth is sited below ground level and, if a damp course is installed, it will be found a couple of courses above the plinth/base. If you can find no evidence of a damp course it would be wise to assume that it would usually be sited at the same level as the foot/bottom of the air-bricks you have already discovered.

Thank you very much for your reply. My feeling is that the protruding bricks should be part of the foundations because they are not damaged (and I would expect some damage if they were exposed at some point in their life) and the older levels of brick/flint are just above this level. It’s amazing/scary how much damage can be caused by the relatively easy and cheap task of layering non-permeable materials on the outside…