Old house - Damp issues

[sheikyerbouti]

mmm. Hadn't thought of BC!

It may be a good thing to be forced down the insulation route anyway as

a) the walls are very very cold (no condensation issues though due to the fresh air system that is installed)

b) There are very few original features left in th ehouse I would want to keep!


Just had my first quote back for Lime render (remove existing cement based, install 2 coat lime render) - £7800. Anyone have any views on this price? Doesn't seem a long way off the price I was given for Cement render.

 

[oversteer]

Boring warning - if you strip off all the render then you may need to insulate the wall (internally or externally) to meet building regulations. Some people avoid this option by not telling Building Control or can use listing to avoid it.

I never realised this either, and it may be pertinent to our situation.
I want to strip the render off then rerender at a later date when funds allow. The wall will be visible from a main road so I wouldn't want to bet on BC not noticing.
I had a quick read through the L1B Building Regs doc, and this seems to suggest that if it is a building of "traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture" special considerations can apply, including "improving energy efficiency as far as is reasonably practicable" including benefits to "enabling the fabric of historic buildings to 'breathe' to control moisture".

So, would a solid-brick built property be counted in this?

L1B here http://www.wall2wallsurveying.co.uk/images/October_2010_Part_L1B.pdf

 

[sheikyerbouti]

Quick update.

I'd forgotten how interesting (and potentially expensive!) digging around in an old house could be! Maybe I should have watched "the money pit" with Tom Hanks a few times before purchasing! :lol:

I took some samples from around the house to determine what it was made of. I took off an air vent cover in the dining room and found a piece of plaster. I also took some plaster from the living room to test as well. All fizzed like crazy in a bath of vinegar so we have some lime!

Lifted the floorboards in the bedroom and found the ceiling to be laths and plaster - all lime based.

However I then thought I would take a sample of plaster in the main bedroom and decided on an area of blown plaster beneath one of our oak beams. As we are fully redecorating and renovating it is not such a big issue. Anyway, after digging some plaster out it seems there was a void behind - depth checking with my longest screwdriver showed me hitting something solid at 9" - basically the hole goes right out to my external render :shock: It is between bricks (I can see brick ateither side of the hole).

I took another 2 samples on the crack, one above and one below. There was no void, however the crack follows the mortar line as shown on my attached piccy.

Interestingly, there is an air vent on this particular line, about 5 feet below the beam. When I took the cover off, this did not turn out to be a traditional air brick and void, but a series of around 20 holes drilled through the brickwork to the outside of the house with a cover on. After initially being mortified by the hole I found, i'm wondering if the use of a huge hammer drill in this area was the likely culprit for the crack.

I've also noticed the crack in the plaster extends slightly in to the living room below.


Grrr! I have a local buildings specialist coming in a week and a half to take a look and advise.

 

[JoceAndChris]

Your poor old house, what terrible things have been done to it. Good luck with the rescue.

Interesting to read the point about the insulation - that would be a disaster for here. Externally, the house needs to breathe, and internally, there are 3 shaped glass bays with shutter housing and cornice and skirtings and wobbly lime plaster. I'd definitely keep quiet. It just seems that these rules are interpreted and applied subjectively and unevenly - very scary when it comes to old buildings.

As regards the quote for the removal of the cement render and rerendering in lime, I think it's pretty good. Mine was 25 k ish for 100 sq m. This was by a National Trust approved team of historic building specialists and included the construction of French drains, the removal of a cemented on York stone plinth and then putting it back without the cement, plus Chatsworth's head plasterer to line out the walls, building up the layers of lime to create a sharp and formal structure scored to resemble ashlar. Not a DIY job. I had other quotes at around 15k but they didn't include the drainage, or the highly skilled replastering. Sadly we've not yet come across a spare 25k but hopefully we will.

 

[plasticpigeon]

I hope I'm not talking out of turn here, but I would think little cracks in the plaster are not a big deal. I would expect the house to have moved a little, and may still move a little seasonally. That makeshift air brick doesn't sound like the neatest solution! If you have a void in the brickwork, I'm sure it can be filled in with a brick or two. The great thing about brick construction is that it is possible to fix or change things reasonably easily., However finding a good brick layer/builder may not be so easy!!!!!! If you take the render off, you will get more idea of what has been changed, and how well the work was done, and then make your choices based on a bit more knowledge. I'm sure you will get it right, but make sure you take your time and make the right decisions!!!!

 

[michael]

I would be careful about removing the external render without getting an expert opinion maybe from your local conservation officer first. Your photograph suggests that modern OPC cement render has been applied over an old external render. I’m sure the new render needs to come off but the old render could be an original Roman cement. Roman cement is breathable but not to the extent of lime and quite often where roman cement has been applied to the outside of a building, the internal face of the building would have a cavity between the lime/hair lath plaster and the brickwork. Unfortunately Roman cement is no longer available now with the exception of this French product which is similar.

http://www.cornishlime.co.uk/promptcement.php
http://www.virginialimeworks.com/products/nhl/vicat.html
http://www.romanportland.net/files/doc/cahier_technique_cr_cnp_eng.pdf

There are a number of suppliers of this product in the UK.

Also that pink stuff at the base of the internal walls looks suspiciously like modern gypsum plaster which is certainly not doing your building any good. It just acts like a sponge. Well worth replacing these surfaces with lime plaster.

 

[AMc]

Boring warning - if you strip off all the render then you may need to insulate the wall (internally or externally) to meet building regulations. Some people avoid this option by not telling Building Control or can use listing to avoid it.

I never realised this either, and it may be pertinent to our situation.
I want to strip the render off then rerender at a later date when funds allow. The wall will be visible from a main road so I wouldn't want to bet on BC not noticing.
I had a quick read through the L1B Building Regs doc, and this seems to suggest that if it is a building of "traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture" special considerations can apply, including "improving energy efficiency as far as is reasonably practicable" including benefits to "enabling the fabric of historic buildings to 'breathe' to control moisture".

So, would a solid-brick built property be counted in this?

L1B here http://www.wall2wallsurveying.co.uk/images/October_2010_Part_L1B.pdf

There is some wiggle room with L1B compliance and older buildings. A sensible officer is unlikely to force you to use inappropriate materials to comply which will result in problems with damp or degrade the overall building BUT most building inspectors are not trained to be experts in historic buildings or energy efficiency so they (rightly) rely on best practice, BRE documents and technical guidelines from manufacturers to ensure solutions in use comply.
If you want to do something that doesn't comply you are going to have to become or employ an expert in both to show that what you propose to do is the best compromise between improving the energy efficiency of your house towards current targets and the long term well being of the house structure. BC are unlikely to be swayed by aesthetic considerations unless you have the added protection of a conservation area, a listing and probably a helpful conservation officer.
In short your chance of being allowed to renew your thermal element with no improvements is pretty slim - otherwise every property developer would be campaigning to do nothing when "flipping" 2 up 2 down terraces.

There are" breathable" ways to meet the regs, unfortunately they are often more expensive & use more space and finding the skills to design and implement them can be challenging.

There are also rules that mean you aren't forced to sacrifice more than a certain area of living space (5% IIRC) or spend sums that can't be calculated as saving money using "simple payback" calculations over sensible time frames (10 years?). Again the default position is likely to be you need to prove compliance or you will not get your approval.

There is a final option which we used. We wanted to renovate a derelict part of the house and bring a non residential vinery and agricultural stores into residential use. The way that we were able to do this was to "over insulate" the renovation well beyond L1B requirements (walls, floor, roof) specify the best glazing possible and fit a heat pump to replace our oil boiler. We paid for a SAP report on the proposed work and current house with the heat pump and a report on a hypothetical compliant extension with oil heating. By demonstrating that our "whole house" had a lower carbon footprint than a compliant oil powered house we were able to obtain our building control approval. This was done using the plans and a paid energy consultant.

It's worth noting that we were plumbing, wiring, rebuilding and replacing some structural elements so it was never going to be an option to "not tell" building control and I' wouldn't have done so anyway.

 

[Roger H]

Part L of the building regs gives considerable lassitude to traditional buildings. Certain classes of historic buildings are expressly exempted from the need to comply with the energy efficiency requirements of the Regulations where compliance would unacceptably alter their character and appearance. This includes listed buildings, locally listed buildings, buildings within conservation areas and 'traditionally constructed buildings'.

The English Heritage companion guide to Part L states that 'traditional buildings' comprises 'Buildings of traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture'. It goes on to say that "this category includes nearly all buildings constructed prior to 1919, as well as a significant proportion of those built before 1945. It is essential that adaptations made to improve the energy efficiency of these structures should take into account the traditional technology and characteristic behaviour of the building fabric, otherwise very real damage can be caused".

Paragraph 3.9 of Part L states that: 'The work should not prejudice the character of the host building or increase the risk of long-term deterioration of the building fabric or fittings'

The EH doc is available at:

http://www.english-heritage.org.uk/publications/energy-efficiency-historic-buildings-ptl/eehb-partl.pdf

 

[Zebra]

Ooh, that's useful, thanks. Not that I have problems with Building Control over my proposed re-rendering. I emailed the Building Control officer, who emailed me back to say that although the current U value requirement is 0.28w/m2K, due to the age of the property I should aim for 0.35w/m2k ( Guidance Approved Document L1B section 1). He said that if I put in an application into Building Control they would enforce this (implying that if I didn't, they wouldn't...... so I haven't).......