UKC

Should my mate use lime mortars and limecrete etc for his house renovation to keep damp (rising and leakage) at bay or standard modern materials. Damp course also seems necessary. Any experiences, pitfalls or ideas and on a climbers budget greatfully recieved. (1875 House in wet wales, flagstones and stone)... total quality wanted...not much eh!

In reply to Arthur Fonzareli (the Fonze): I've had this problem - a bloody good damp course from a reputable and properly insured/ accredited provider is the best way forward.

In reply to Arthur Fonzareli (the Fonze):

There's a lot of evidence to suggest that rising damp is a myth. Damp proofing companies always invariably insist you need one, even in cases where the damp is clearly penetrating damp or condensation. They cost a lot, and generally aren't necessary, unless you live in a sponge house.

I've even known a damp proofing company come out and suggest a new silicone injection DPC on a house with huge holes in the pointing between the stonework, through which rainwater was entering. Even most of the 'reputable' companies just have a knee-jerk DPC policy. And they will all insist that rising damp is a fact because most of their business depends on it. Try Googling 'rising damp myth'.

This is a reasonably balanced blurb from the Centre for Alternative Technology:

http://tinyurl.com/3864h4

In reply to Arthur Fonzareli (the Fonze):

P.S. I rebuilt a stone cottage in Wales using lime mortar etc, didn't install a DPC, and still no damp problems about 7 or 8 years later (I know this is true because my mother lives in it!). Membrane (Visqueen) under the flags, obviously, to prevent basic soaking through, but no DPC in the walls.

In reply to Steve Parker: hmm. I had a severe damp problem. I had a new DPC and replastering. The damp went away. I take your point that DPC companies will always find damp, but my contractor didn't do the survey.

In reply to toad:

What kind of plaster did they use? If they used damp-proofing and salt-resistant plaster, then that might well have fixed a penetrating damp problem, at least for the short term. I've known several people have the same treatment, and eventually the damp came back, long before the DPC would have broken down. Check out Mike Parret's website. He's investigated something like 5000 cases of 'rising damp', and reckons he's yet to find a single genuine one (and he's not alone):

http://www.dampbuster.com/

He's no cowboy either:

http://www.dampbuster.com/curriculum_vitae.pdf

In reply to Steve Parker: that figures.... did you set any flagstones down and how does the water vapour/damp/condensation etc seem to do with heating which is likely to be central/woodburner/underfloor heating.... also.... does this guy travel/easy to use as a consultant...or will reading a book be easy to diagnose.. cheers

In reply to nellingtonbywold: also...can eco building get cheaper soon.... all the newspapers seem to give eco building a lot of spin.. we have ty calch lime 25 miles down the road near llangorse and it provides the mortars and cretes ... any tips steve?

In reply to nellingtonbywold:

The CAT will know a lot more about it all than me:

http://www.cat.org.uk/information/info_content.tmpl?subdir=information&...

Regarding condensation - yeah, it's a big problem in any old house, and you need to insulate wherever you can to avoid cold spots etc (drylining cold walls instead of just plastering them, for instance). Ventilation is important too, obviously, especially in bathrooms and bedrooms.

The cottage I rebuilt had a gravel-filled trench a few inches below ground level around most of the house, which helps drainage helps avoid penetrating damp. Seems to have worked okay.

In reply to Arthur Fonzareli (the Fonze):
Traditional building method has a completely different approach to modern ones. With traditional material like natural stone wall with lime mortar, limecrete floor and slat roof everything breathes. That's why if your wall trap moisture after rain the vapour will breath out and keep things dry in long term. It works like a thick woolen jumper.

Standard mordern construction works in a different logic. As most of the man-made materials don't breath (such as reconstituted stone cladding, concrete roof tiles and concrete floor slab). If you trap moisture (from rain and internal condesation) in the building components (such as structural timber) and the vapour can't escape that's how damp problem is caused. Two ways to prevent the problem are to stop water reaching vunerable material (by the use of DPC, DPM, vapour barrier and breather membrane) and provide ventilation gap in between layers. It works like a modern double layer tent.

To combine modern and traditional materal sometime it's tricky as the two systems clashes with each other. There's no standard answer.

On lime mortar - the reason you shouldn't use modern cement based mortar on natural stone is because they don't breath like lime. As water tends to be pushed out the more breathable material the stone will gradually wear out quicker then the cement. With lime mortar the vapour can escape in between the gaps.

I don't know much about limecrete but I guess it will let moisture escape upwards so you shouldn't need a damp proof membrane. If you replace it with concrete slab a DPM is a must. You can also build a suspended timer floor but make sure you vent the solum with air brick. DPM is still needed.

Nowadays building control officer will usually ask for DPM and DPC unless you are doing a complete traditional construction.

For more information about lime you can visit the Scottish Lime Centre website:
http://www.scotlime.org

I think it will be worthwile to talk to a consultant (architect/building technologist) or ask your local building control officer's opinion. Spending little consultant fee now might save long term trouble.

By the way this is my job I design and draw up building details everyday. Hope this is useful for you.

If you decide not to pay a consultant you can also ask some manufactuers to do a 'condensation risk analysis' for free. Just contact the technical department and tell them exactly what materail you're going to use in each layer and they'll tell you whether damp will build up in different times of the year. Companys who do those free services include insulations (Kingspan, Celutex, Rockwool..) and breather membrane manufacturers (Protor, Tyvek...). Obvious they will try to sell you their products and usually they're not too helpful with tradional materials.

In reply to Arthur Fonzareli (the Fonze):

My parents are at the end stages of renovating a crofting cottage on Arran, and decided to go down the lime route. The house is rubble stone walls built on a slate flagstone foundation.

The house was rendered (with big cracks), had lots of concrete patchwork on the outside and the inside of the walls, and the soil layer was up to 50cm above the slates at one end of the house. it had been uninhabited for years, and was very very damp.

The concrete has all be ripped out, and lime pointing reapplied to all the walls. They've decided not to render the outside. When the concrete was chipped off, the stone undrneath was saturated, not nice...

The single most important thing I think they have done is dig a a drainage ditch round the bottom of the walls, inside and out, to bring the soil level down to the slate flags. This means that damp cannot penetrate into the stones and rise from there. They've put in new joists and a suspended wooden floor, with insulation/membrane underneath. House is now dry, and looking great. You will need a dehumidifier, and it will take a lot of use...

If you look at damp companies, they will probably recommend you get a solid floor complete with DPC, and install some kind of DPC in your walls. You may need neither, especially if you have a slate layer at the bottom of your walls, as this is a DPC, as long as the soil level doesn't breach it.