Green Building Forum - Preventing water ingress in a stone building Tue, 19 Dec 2023 04:01:41 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304435#Comment_304435 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304435#Comment_304435 Fri, 01 Dec 2023 11:52:56 +0000 JulesS The building is cut into a hillside with a narrow void between the rear wall and the hill, over the years this void has filled in with earth. Directly behind the building is a road (single track).

Our problem is there is a lot of water finding its way into the building. In an ideal world we'd dig out the void down to below final floor level and install a drain to move the water away before it gets to the building. However because the road is so close to the back of the building if we dig it out we'd be worried about undermining it. In the long term we want to insulate externally (wood fibreboard), so getting down to this level would be awesome.

From an inspection pit we can see that the original depth of the void is about 60cms higher than the final floor level so if we did dig down we'd be going lower than they originally did. There is some evidence of a retaining stone wall holding the bank back, but it's in very bad condition and has been pushed about by trees.

Digging out the void will be difficult as there's no real access for machinery, so probably would have to be done by hand.

Our current thoughts are: dig it out section by section to below eventual floor level installing a drain, put a porous membrane in and backfill with gabions filled with FGA to the original void level... I've no idea if this is a good idea or feasible, we've come to this by chatting it over with our architect and an SE. I've attached an indicative section of this.

I would love folks' opinions on this, and am open to any ideas on how to tackle it. We'd also be really grateful if folks could suggest a professional with specialism across old buildings, civil engineering (?) and drainage we could get advice from, as we're really struggling to get specific help with this.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304436#Comment_304436 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304436#Comment_304436 Fri, 01 Dec 2023 12:00:11 +0000 JulesS Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304437#Comment_304437 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304437#Comment_304437 Fri, 01 Dec 2023 16:20:43 +0000 djh Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304438#Comment_304438 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304438#Comment_304438 Fri, 01 Dec 2023 16:56:56 +0000 Nick Parsons Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304440#Comment_304440 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304440#Comment_304440 Fri, 01 Dec 2023 17:08:35 +0000 philedge
If your section is in proportion then it looks to me like you'd have no problem getting down to your foundations without short term undermining of the road, but....there's the issue of retaining the land between the road and your wall. If there's an existing retaining wall its likely being partly supported by the filled void bearing on your house. If your house is structurally up to it then no harm in filling the void with insulation, but if it's not then you'll be opening a structural can of worms compounded with uncertainty over the boundary!!]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304460#Comment_304460 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304460#Comment_304460 Sat, 02 Dec 2023 23:10:33 +0000 JulesS
Thanks for your responses...

Posted By: djhIs it a normal public road, although single track?


yes, public road. Very low traffic, but occasionally very heavy farm machinery etc.

Posted By: philedgeIf your section is in proportion then it looks to me like you'd have no problem getting down to your foundations without short term undermining of the road, but....there's the issue of retaining the land between the road and your wall. If there's an existing retaining wall its likely being partly supported by the filled void bearing on your house. If your house is structurally up to it then no harm in filling the void with insulation, but if it's not then you'll be opening a structural can of worms compounded with uncertainty over the boundary!!


The section is correct for that section :). But it narrows significantly to a point where the road edge is about 90cms away from the wall. With a 50cms void (minimum for human access?), this is getting extremely tight....

If it was infilled with blown glass, would this replicate the potential structural nature of the current soil infill?]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304461#Comment_304461 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304461#Comment_304461 Sun, 03 Dec 2023 10:57:40 +0000 Peter_in_Hungary Posted By: JulesSyes, public road. Very low traffic, but occasionally very heavy farm machinery etc.
Is it a public road owned by the local authority or private land with a public right of way?

Stone walls with rubble infill are not by any means classed as retaining walls capable of taking side thrust or pressure. AFAIK pressure through soil is calculated at an angle of 45 deg. so if you take a line the edge of the road at 45 deg. it is below this line that pressure from the road will affect the wall. Not only is it the pressure of the traffic but also the standing pressure of the soil. The loads on the wall will be worse if the road is bumpy as this will introduce additional vibration.

Normally the loads from structures adjacent to a building are designed to pass below the foundations i.e. a 45 deg. line from the base of the structure should pass below the foundations of the building.I suspect that the road and the building have been there for some time, probably before the weights of today's vehicles were on the road. I would be concerned that the road and its traffic are now exerting an unacceptable side thrust on the wall of the building.

If it were mine I would not be disturbing the soil between the road and the house until the SE has confirmed what is acceptable. Once the SE has commented on the structural stability of the whole situation then you may find your self talking to which ever authority has control of the road given that I suspect that the construction is nowhere near today's standards and I would be surprised if any insurance co. would entertain a claim in the event of movement in your wall.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304464#Comment_304464 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304464#Comment_304464 Sun, 03 Dec 2023 18:54:22 +0000 JulesS
Thanks very much, that's very useful information. It's a public road owned by the local authority.

Regarding a SE, I think we're probably outside the expertise of the one we've been using for the building, is it civil engineers I need to be looking for? If anyone has any recommendations, I'd very much appreciate it (West Wales).

Jules]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304465#Comment_304465 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304465#Comment_304465 Sun, 03 Dec 2023 19:10:43 +0000 JulesS model), and I've just been putting some angled planes into it and it does indeed hit the foundations - pretty much all along the road side. So would this mean (SE approval pending), any thing above this angled line is essentially fair game for removal?

Many thanks,

Jules]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304466#Comment_304466 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304466#Comment_304466 Sun, 03 Dec 2023 19:14:43 +0000 philedge
Rather than you engaging and paying for a structural/civil engineer it might be worth contacting your local highways dept and explain that you want to clear out the void between the house and retaining wall due to damp ingress and ask them to confirm the road is adequately supported when not bearing on your house]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304467#Comment_304467 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304467#Comment_304467 Sun, 03 Dec 2023 20:32:33 +0000 JulesS
Thanks, that's a good idea.

I'd be interested to hear what people's opinions are in terms of 'is it best to involve the local authorities or not?'. I've spoken to a few people who have warned us off approaching the council unless legally required (general consensus of it slowing everything down and becoming very bureaucratic), I'd love to hear folks' opinions on this.

Having said that, our personal experience of the council has been positive and we're open minded and want to do the best / safest thing so would just value others input on this.

Jules]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304468#Comment_304468 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304468#Comment_304468 Sun, 03 Dec 2023 20:45:08 +0000 Peter_in_Hungary Posted By: JulesSRegarding a SE, I think we're probably outside the expertise of the one we've been using for the building, is it civil engineers I need to be looking for?
Ask the SE you are currently using as they might know someone who has that expertise.

Posted By: philedgeRather than you engaging and paying for a structural/civil engineer it might be worth contacting your local highways dept and explain that you want to clear out the void between the house and retaining wall due to damp ingress and ask them to confirm the road is adequately supported when not bearing on your house

Now that's a good idea !!

Cross posted with JulesS - If you are going to mess with the LA road in terms of removing support they have been relying upon for their road then you have to contact them.

There are regs about supporting the sides of ditches in which you are working (elf an safety) to prevent the sides collapsing and crushing the workers. These will need t be followed if you are digging next to a LA road.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304469#Comment_304469 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304469#Comment_304469 Sun, 03 Dec 2023 20:46:55 +0000 djh
You mentioned there was some uncertainty about the land boundary. Is your plot not registered? If it is there shouldn't be much dispute. Who mows the verge of the road and who pays for it? And how wide do they mow?]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304470#Comment_304470 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304470#Comment_304470 Mon, 04 Dec 2023 08:23:36 +0000 Peter_in_Hungary Posted By: Peter_in_HungaryAFAIK pressure through soil is calculated at an angle of 45 deg.

Posted By: JulesSSo would this mean (SE approval pending), any thing above this angled line is essentially fair game for removal?

Not quite. 45 deg. is the typical. It will vary depending upon the soil type. E.g.disturbed soil or gravel will need a lower angle and rock can be steeper. So investigation will be needed before the safe angle can be decided upon.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304471#Comment_304471 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304471#Comment_304471 Mon, 04 Dec 2023 09:25:38 +0000 fostertom Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304472#Comment_304472 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304472#Comment_304472 Mon, 04 Dec 2023 09:50:26 +0000 Peter_in_Hungary Posted By: fostertomYou say the 45o (or soil-type-appropriate angle) plane 'hits the foundations'. For static ground pressure + pressure from weight of vehicles that should be OK as long as the plane doesn't 'penetrate' the house interior but passes below interior floor level. However, yes if vehicles cause vibration that could have wider effects, don't know how to assess that.
But Jules said
Posted By: JulesSBut it narrows significantly to a point where the road edge is about 90cms

and looking at the diagram above with the ground level outside being a bit below ceiling level it seems unlikely that the 45 deg angle at this point would only hit the foundations and miss the wall.

It looks a bit marginal at best so details are needed. And with a stone / rubble wall I wouldn't take any chances. Certainly if it narrows to 90cm and a 50cm trench is dug then this only leaves 40cm supporting the side of the road - IMO a recipe for trouble.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304474#Comment_304474 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304474#Comment_304474 Mon, 04 Dec 2023 11:35:03 +0000 djh https://www.nidirect.gov.uk/publications/apply-excavate-near-road ) that says "If you want to make an application for consent to carry out excavations near a road you can use the application form below. As a guide, anything within 12 metres could be regarded as being near a road."

Given the uncertainty about ownership, and about digging near a road, I would definitely suggest consulting either or both of a solicitor and your local county councillor.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304478#Comment_304478 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304478#Comment_304478 Mon, 04 Dec 2023 18:26:17 +0000 philedge
In respect of LA involvement there's the remnants of a retaining wall that I'd guess was the LAs responsibility to maintain if its holding up the road?? Rather than ask if its OK to excavate and risk them saying no, I'd be tempted to tell them you're going to excavate regardless as you believe the road bearing on your property risks damaging it and the infill is causing damp.

If you're not sure of the boundary it might be worth checking your deeds to make sure the retainng wall isn't yours and yours to maintain!!]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304481#Comment_304481 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304481#Comment_304481 Mon, 04 Dec 2023 20:58:19 +0000 Jeff B Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304485#Comment_304485 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304485#Comment_304485 Tue, 05 Dec 2023 09:21:30 +0000 fostertom Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304534#Comment_304534 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304534#Comment_304534 Fri, 08 Dec 2023 12:40:30 +0000 andrew_rigamonti
Or don't tell them and get some gabions with EPS along the house.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304539#Comment_304539 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304539#Comment_304539 Fri, 08 Dec 2023 15:13:34 +0000 Peter_in_Hungary Posted By: andrew_rigamontiOr don't tell them and get some gabions with EPS along the house.
I would be concerned about the pressure on the stone/rubble wall with that approach.]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304544#Comment_304544 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304544#Comment_304544 Fri, 08 Dec 2023 20:22:54 +0000 JulesS
Thanks, Jules]]> Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304547#Comment_304547 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304547#Comment_304547 Fri, 08 Dec 2023 22:02:38 +0000 djh Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304566#Comment_304566 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304566#Comment_304566 Tue, 12 Dec 2023 17:24:45 +0000 GreenPaddy Preventing water ingress in a stone building http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304662#Comment_304662 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18041&Focus=304662#Comment_304662 Mon, 18 Dec 2023 12:42:17 +0000 JulesS