Jump to content


ebuild is sad to announce its closure - it has become too time and resource intensive to develop, manage and maintain.

However, ebuild will remain on-line in archive mode (ie no posting facilties) for several weeks so that users can use it as an information resource.

Any Advice On Driving Rain Ingress On Dressed Stone Wall?


  • Please log in to reply
13 replies to this topic

#1 Stonewall

Stonewall

    New Member

  • Members
  • Pip
  • 2 posts

Posted 27 December 2015 - 10:24 PM

Hello, We are renovating part of a lovely old stone building from mid 19th century in rainy Wales. We have hacked off the internal plaster and are now down to the original thick stone wall which we want to leave exposed or paint with limewash. Externally we do not have the option of rendering with lime or any other kind of render since the dressed stone is a feature of the building. To protect the wall, the outside was recently repointed, (Unfortunately this was not done with lime based pointing but with cement) However, after a few weeks of being lashed with driving rain, the south-facing front of the properly has had a soaking and the damp has come right through to the inside. Our builder has suggested putting some sort of invisible impermeable coating on the outside but this seems to go against the principle of allowing the walls to breathe naturally. Is the only other option to reduce the humidity iinside and if so, what is the most effective way to do this? The room affected by the damp is not being heated at the moment but I can't help thinking that if it was, the humidity problem would be even worse. Thanks for any advice!

#2 ProDave

ProDave

    Self build in the Highlands

  • Moderators
  • 5,960 posts
  • LocationScottish Highlands

Posted 27 December 2015 - 10:32 PM

These very thick walls are often two skins, inner and outer, and rubble / dust in between. For water to come all the way through it would have to be very wet.

I would suspect in view of the "no heating" that condensation is more likely.

My Brother in law lives in a 300 year old Welsh farmhouse. The one wall that is pointed exposed stone inside often has puddles in one corner. The rest of the house has plastered upper walls and timber wainscot to the lower half of the wall and never suffer an (visible) dampness.

Render was often applied later on in an attempt to keep rain out.

Edited by ProDave, 27 December 2015 - 10:33 PM.


#3 joiner

joiner

    Advanced Member

  • Moderators
  • 10,718 posts
  • LocationWest Midlands

Posted 27 December 2015 - 10:39 PM

:) Welcome, but deepest apologies for being rendered speechless by whoever did that to the wall "of a lovely old stone building from mid 19th century in rainy Wales."

Re-point with lime - WHEN the rain stops!

You obviously have an understanding of what the building needs and appear willing to live with it, the question is for how long? Just how dedicated are you to the idea of living with bare stone walls internally?

And what was the nature of the internal plaster you've just hacked off?

#4 ferdinand

ferdinand

    Advanced Member

  • Member Blogger
  • PipPipPipPip
  • 1,031 posts

Posted 27 December 2015 - 10:55 PM

The traditional solution would be to render it outside. Who is stopping you? Perhaps render except for the quoins would look equally attractive.

Alternatives might be to be judicious as to which bits you expose on the inside, and board out that part with an air gap which is vulnerable, perhaps ventilated.

How did the Victorians deal with it? Perhaps linenfold panelling, which is just posh boarding out.

People have used hemcrete on the inside if your rooms are large enough to lose 100mm each way.

Or shelter the wall from DRIVING rain on the outside, which suggests appropriate trees or perhaps a creeper growing up the wall, which since you are recently repointed could be ivy, or to be more benign could be Virginia creeper, perhaps even supported on horizontal battens a couple of inches out if you are squeamish.

Bare stone walls do not need painting, but they are very dusty. You could coat the inside instead to get a sort of moisture membrane. We did that above a bath, and it was fine - but you need the right stuff.

Ferdinand

Edited by ferdinand, 27 December 2015 - 11:00 PM.


#5 tonyshouse

tonyshouse

    Advanced Member

  • Members
  • PipPipPipPip
  • 1,297 posts
  • LocationThames Valley

Posted 28 December 2015 - 08:24 AM

Repoint with lime,

#6 doofaloofa

doofaloofa

    Regular Member

  • Members
  • PipPipPip
  • 550 posts
  • LocationWesht Cark

Posted 28 December 2015 - 10:23 AM

I would concur with Ferdinand about rendering

Leaving stone buildings exposed is a modern affectation, usually to show off the lovely stone

An exposed stone house in the past was a sign that the inhabitants had fallen on hard times and could not keep up the render when it failed, or the dwelling house had been turned into an animal house after a bigger house was built

Lime render and yearly white washing was the traditional solution

#7 ferdinand

ferdinand

    Advanced Member

  • Member Blogger
  • PipPipPipPip
  • 1,031 posts

Posted 28 December 2015 - 04:28 PM

Having said that, *this* was our exposed stone house, which I don't think had ever been rendered since Lizzie I, but it is in a valley and south facing with more trees than Sherwood Forest. It has at one time (1900) been completely covered in ivy - and I mean completely.

The bits around the arched window that look rough show what good stonework looks like after 100+ years of ivy. If you have repointed you would not need to worry, unless you are founding a dynasty. All the other parts of wall you can see had been worked on by an old school stonemason over a 25 year period.

http://www.rightmove...y-29776285.html

Pictures 10 and 11 show the bedroom with the ensuite I was talking about. You can just see the bath in piccie 11!

If you do leave that sort of amount of stone exposed you may need an industrial hoover, and lots of MVHR (?) filters.

Ferdinand

Edited by ferdinand, 28 December 2015 - 04:35 PM.


#8 Mackers

Mackers

    Regular Member

  • Members
  • PipPipPip
  • 233 posts
  • LocationBanbridge

Posted 28 December 2015 - 05:13 PM

Nice house!

#9 doofaloofa

doofaloofa

    Regular Member

  • Members
  • PipPipPip
  • 550 posts
  • LocationWesht Cark

Posted 28 December 2015 - 05:16 PM

Have you a pic of your wall Stonewall?

#10 jsharris

jsharris

    Please ignore all posts by me, some are erroneous

  • Member Blogger
  • PipPipPipPip
  • 11,461 posts
  • LocationWiltshire/Dorset border

Posted 28 December 2015 - 07:01 PM

I've lived in, and had to deal with, a few damp problems in stone houses. It's worth remembering a few basic facts:

1. Most building stone, is, to all intents and purposes, waterproof, and water very rarely actually penetrates through even semi-permeable stone, like sandstone.

2. 99% of damp problems in stone buildings arise from penetrating moisture, not "rising damp" or other semi-mythical effects like "stone needing to breathe".

3. Curing damp in stone buildings needs thinking logically about the causes, and the best mitigation strategy for the particular type of building and its use.

The first line of defence is to minimise water actually hitting the walls. Rainwater isn't often a major problem, leaking gutters and downpipes often are.

Next, ensure the pointing is sound and compatible with the type of stone the outer face of the wall is made from. 9 times out of ten this means using a semi-flexible pointing material, based on lime, rather than any form of cement product.

Take care to ensure that the lower part of all outer walls is exposed below the internal floor level and that good drainage is provided all around the outer walls. It is rare for any form of damp proof course to be needed in reality, even if lenders insist on fairly useless treatments like silicone injection. Rising damp is both rare and easily fixed by ensuring that the outside ground level is lower than the inside floor level and that it is well-drained (consider adding French drains around the outside of any particular problem walls)

The major problem faced with trying to make older stone buildings as comfortable as modern homes is with ventilation and internal water vapour control. At the time that these houses were built, internal ventilation rates would have been high (because of lots of air leakage through doors and windows, plus the high air change rate that open fires create). We try to improve the heating efficiency and comfort level of older homes, by sealing up draughts, increasing internal temperatures with central heating and decreasing natural ventilation, whilst introducing additional sources of water vapour from showers, hot baths and modern cooking methods. The result is relatively high internal humidity that can then condense on colder parts of the structure causing damp.

There is no "one size fits all" cure, but rather a series of investigations and the selection of the best remedy for each problem. Things worth considering (once any major defects in the structure have been fixed, and appropriate lime mortar repointing has been undertaken where needed, include single room heat recovery ventilation for bathrooms, kitchens and utility rooms, and, perhaps, positive pressure ventilation for the whole house to improve air circulation and reduce humidity levels. The latter is not particularly energy efficient, and for me would be a very last resort, but there is no doubt that it can be extremely effective in older houses.

#11 ferdinand

ferdinand

    Advanced Member

  • Member Blogger
  • PipPipPipPip
  • 1,031 posts

Posted 28 December 2015 - 08:53 PM

View PostMackers, on 28 December 2015 - 05:13 PM, said:

Nice house!

It is a glorious bruiser of a house.

There are a lot of tales here ! The last serious maintenance has been in the late 19c. All of those beams and about 15 sets of original Georgian shutters were scraped of 150 years of paint by my mother doing half a square foot every night after work for years.

That arched window was rotten and remade from scratch by a local carpenter, and the Jacobean galleried staircase was restored by 2 furniture students spending a whole summer holiday with us.

It is the type of house like a 1970s Ferrari - either you have the time and ability to many jobs yourself and good trade contacts, or you budget 5k to 10k per annum forever just to stay on top.

For an insight into the local market in 2013, that price had already been dropped by 12%, and we dropped it by a further 20%+ to sell. The incoming people would need within a few years to spend 10-20k on just bringing the trees into order.

It needs the next lot of people who are going to live there for 35 years so that they can justify spending 150k or 200k now on Eco heating and all the rest.

Ferdinand

Edited by ferdinand, 28 December 2015 - 08:58 PM.


#12 ferdinand

ferdinand

    Advanced Member

  • Member Blogger
  • PipPipPipPip
  • 1,031 posts

Posted 28 December 2015 - 09:01 PM

View Postjsharris, on 28 December 2015 - 07:01 PM, said:

I've lived in, and had to deal with, a few damp problems in stone houses. It's worth remembering a few basic facts:

1. Most building stone, is, to all intents and purposes, waterproof, and water very rarely actually penetrates through even semi-permeable stone, like sandstone.

2. 99% of damp problems in stone buildings arise from penetrating moisture, not "rising damp" or other semi-mythical effects like "stone needing to breathe".

3. Curing damp in stone buildings needs thinking logically about the causes, and the best mitigation strategy for the particular type of building and its use.

The first line of defence is to minimise water actually hitting the walls. Rainwater isn't often a major problem, leaking gutters and downpipes often are.

Next, ensure the pointing is sound and compatible with the type of stone the outer face of the wall is made from. 9 times out of ten this means using a semi-flexible pointing material, based on lime, rather than any form of cement product.

Take care to ensure that the lower part of all outer walls is exposed below the internal floor level and that good drainage is provided all around the outer walls. It is rare for any form of damp proof course to be needed in reality, even if lenders insist on fairly useless treatments like silicone injection. Rising damp is both rare and easily fixed by ensuring that the outside ground level is lower than the inside floor level and that it is well-drained (consider adding French drains around the outside of any particular problem walls)

The major problem faced with trying to make older stone buildings as comfortable as modern homes is with ventilation and internal water vapour control. At the time that these houses were built, internal ventilation rates would have been high (because of lots of air leakage through doors and windows, plus the high air change rate that open fires create). We try to improve the heating efficiency and comfort level of older homes, by sealing up draughts, increasing internal temperatures with central heating and decreasing natural ventilation, whilst introducing additional sources of water vapour from showers, hot baths and modern cooking methods. The result is relatively high internal humidity that can then condense on colder parts of the structure causing damp.

There is no "one size fits all" cure, but rather a series of investigations and the selection of the best remedy for each problem. Things worth considering (once any major defects in the structure have been fixed, and appropriate lime mortar repointing has been undertaken where needed, include single room heat recovery ventilation for bathrooms, kitchens and utility rooms, and, perhaps, positive pressure ventilation for the whole house to improve air circulation and reduce humidity levels. The latter is not particularly energy efficient, and for me would be a very last resort, but there is no doubt that it can be extremely effective in older houses.

+1 to trenches round the outside. That was the first thing we did to a Depth of 18 inches because the ground level outside was above the inside. But watch for possible non-existent foundations.

F

#13 joiner

joiner

    Advanced Member

  • Moderators
  • 10,718 posts
  • LocationWest Midlands

Posted 29 December 2015 - 07:03 AM

:) To repeat...


Re-point with lime - WHEN the rain stops!

Stonewall - You obviously have an understanding of what the building needs and appear willing to live with it, the question is for how long? Just how dedicated are you to the idea of living with bare stone walls internally?

And what was the nature of the internal plaster you've just hacked off?

;)

#14 Stonewall

Stonewall

    New Member

  • Members
  • Pip
  • 2 posts

Posted 10 February 2016 - 12:43 PM

Hello,

I had not realised that a number of people had posted replies to my query so a belated thank you to those of you who offered advice and comments.

To the person who asked why I could not render the property externally, it is because it is one wing of a big old building so would look weird to have only one bit rendered.

With the unusually high levels of rain in the past couple of months, even by Welsh standards, the front elevation wall continues to be thoroughly soaked but I think I may have found a solution which I would like to share with forum members. A company in Brecon called Ty Mawr, which specialises in lime products, sells a product called Sufapore which apparently stops water droplets from penetrating the stone but is not a barrier to water vapour, so the stone retains breathability. Has anyone tried using this? The only problem is I will have to wait ages for the stone to dry out. I read somewhere that it can take a year and a half! Thinking I will start heating the house internally soon, and/or put a dehumidifier in there and then wait until perhaps late August to apply Surfapore to the outside of the wall.
Internally I am lime plastering some walls and limewashing others, work which is being carried out by a company recommended by Ty Mawr.

I would like to say one more thing which is that Cadw, the Welsh heritage buildings organisation, was disappointingly unhelpful when I contacted them for advice, because the property is not a listed building. They were just not interested. Shame on you Cadw!

I will update this post later with pictures of the work if anybody is interested. Thanks again!