Advice on renovation

[rherbert]

hey all

need some advice on renovating my property. property is:

- red brick with a wooden crook frame
- no foundations brick shell on clay
- three downstairs rooms one is suspended wood floor the other two are solid with a bitumen covering
- walls have been driled and have a chemical damp course
- all walls have normal pink plaster on them
- upstairs floors are lime ash on reeds on top of oak beams
- kitchen is made of brick but is a lean to construction on the back of the house

we have some problems:

- there are some damp patches showing in the plaster mainly in the room with the suspended wood floor and on the interior walls
- the suspended wood floor has rotted and is unusable its like sponge
- bricks in the kitchen are degraded, it is a new addition and looks unsightly

we would like to modernise the property and make it a little more efficient:

- replace the suspended wood floor with a solid floor as we cannot ventilate the floor space
- install exterior wall insulation
- replace single glazed windows with double glazing
- knock down kitchen and replace with an extension which fits the period looks of the house
- install underfloor heating to all rooms
- install loft insulation

my ideas for these changes are as folows:

- pink plaster hacked off to 1m and replaced with lime plaster or renovation plaster (i'm not sure what the difference is here, is the renovation plaster still breathable?)
- exterior walls batonned and cellotex insulation attached then plaster board over the top (i read this can cause interstitial condensation and in the future mould problems is there any way to ventilate this to reduce the likelehood? they currently have no signs of damp even though covered in pink plaster)
- with the undefloor heating make a channel around the edge of the concrete slab about 6 inches wide which would be filled with limecrete to allow the moisture trapped under the floor to evaporate (would this work had seen it done here http://www.mikewye.co.uk/limecrete_Hybrid_Floor.htm)
- install french drains on the exterior walls
- normal fibre insulation in loft but install vents to help the roof breath and when the property is re roofed install a breathable membrane under the slate

any advice on construction methods and materials would be greatly appreciated

richard

 

[middi]

Well, you certainly need a bit more than a lick of paint.
When you say " crook frame" do you mean " crack" frame construction, if this is the case I can only assume that your house already underwent a major restoration attempt a few hundred years ago as bricks were not the order of the day when crack frame houses were constructed.

Due to the nature and extend of the repairs you need to do, it would be wise to invest a bit more money and engage the services of a " period houses" architect that can guide you through the application and usage of modern materials, how these can suitably be applied to your situation and the least impact they have on the " period" look.
The materials you are contemplating to use is fine, as long as they are used in a manner that will not interfere with the wellfare of the original structure , their quality and performance should complement the needs of any original building fabric that will not need to be disturbed.

If a conservation officer needs to be consulted, they can be an excellent source of information and guidance to your restoration plans.

Middi

 

[Keith Bowman]

Cruck frame perhaps? Like a big wishbone: one piece of timber each side of each frame, curving up from the ground to the ridge?

 

[Moo]

I have a feeling that someone will soon come along demanding pictures, so if you haven't done so already I suggest you get busy with your camera asap.

 

[middi]

Cruck frame perhaps? Like a big wishbone: one piece of timber each side of each frame, curving up from the ground to the ridge?

Well done Keith, yes " CRUCK" frame.

Middi

 

[Zebra]

- exterior walls batonned and cellotex insulation attached then plaster board over the top (i read this can cause interstitial condensation and in the future mould problems is there any way to ventilate this to reduce the likelehood? they currently have no signs of damp even though covered in pink plaster)
- with the undefloor heating make a channel around the edge of the concrete slab about 6 inches wide which would be filled with limecrete to allow the moisture trapped under the floor to evaporate (would this work had seen it done here http://www.mikewye.co.uk/limecrete_Hybrid_Floor.htm)
- install french drains on the exterior walls

richard

The difference between lime plaster and renovation plaster is that the former is breathable and the latter is the very opposite, is a waterproofer and will not allow your walls to breathe.
There is a total different philosophy and approach to be considered when dealing with houses built before cement and damp-proof-courses were invented. Old houses were designed to breathe, and for any water vapour or moisture which built up in them - be it in the walls, the floor, or the roof - to evaporate away.
I've not done it myself but I believe I've read on here and elsewhere (GreenBuildingForum) that the use of celotex internally on solid brick walls can cause damp to build up behind the celotex and can cause mould. Ventilating behind the insulation would be tricky to achieve effectively I would think, and would cut down the effectiveness of the insulation. It is better to insulate solid walls externally if you can, so that the thermal mass of the wall is on the warm side, not the cold side, of the insulation. Breathable insulation materials are also available to avoid trapping of moisture.
There's not one given answer to your dilemma I don't think. I pondered long and hard and asked for much advice before choosing a system for my house, and I can only advice learning as much as you can about breathability, condensation, etc, before making your decision. There's an excellent article on the subject here http://www.greensteps.co.uk/tmp/assets/1163178050906.pdf.
I know everyone on here will advocate taking time to assess what works for your property before undertaking drastic measures which may prove unneccessary, so I won't reiterate that point! But I know with mine it was (still is) a case of doing one thing and taking the time to see whether that's worked before trying something else. Presumably you've checked for faulty rainwater goods, external ground levels higher than inside, and all those typical causes of damp, before thinking about french drains and limecrete trenches?

 

[MatthewC]

Hi Richard

You certainly have got a real challenge on your hands: bitumen, gypsum, injected dpc... You'll find lots of relevant (and some very irrelevant!) advice already on this forum if you search the old e-mails.

Is it listed? If so, you might have some problems with your conservation officer in getting your proposals agreed, although you should easily get permission for a new kitchen if it's a collapsing brick lean-to. Also, don't forget that Building Control will want to be involved especially when you do your roof.

As a priority, as Zebra says, you should try and do as much as you can to stop water getting in - check high ground levels, drains, gutters, roof etc. Then you should aim to do as much repair as possible using only breathable materials - but don't do permanent changes in a hurry without long debate.

I would think that your Celotex wall insulation idea might not be a good one in the long run (but I didn't have to add any insulation to my 18" stone walls!). I also used a breathable insulation (Thermafleece PB20 from Mike Wye) in the loft as we put breathable plaster on the lath ceilings. (I'm not sure if Thermafleece could be used on the walls?) The hybrid floor seems to be a good idea as an alternative to digging up the concrete to do a complete limecrete floor!

I have a suspended floor which was rotten at the edges and required extensive repair. It won't happen again as the floor level concrete outside has been removed, the underfloor ventilation now works (concrete lump removed) and the gutters work! However, you could fit a limecrete floor if you think it will still get damp.

Let us know how you get on. Click the blue button on the right to see my blog.

Matthew