Curing damp problem in an old property (timber framed)

[keithsh]

We live in a timber framed, cob walled cottage, built on a brick plinth. The floor comprises mainly Suffolk pamment floor bricks.
We are experiencing damp in one wall. We have been told by a builder that this is rising damp from floor level (the cottage is built on clay and has no foundations) up the bricks and up to and affecting the sole plate which sits on the brick plinth. Different builders have proposed different ways of solving the damp issue. We know that we need to keep the wall breathable but we are getting confused about the differing proposed remedies. It seems that the options are to:
• Dry line the wall with lime plastering over this
• Drill holes in the wall, pump in a breathable sealant and then lime plaster over this
• Put a “membrane” between the top of the brick plinth and the oak beam soul plate to stop damp reaching the soul plate and then lime plaster over this
• Put a membrane under the brick floor and then lime plaster the wall.
We seek advice about the effectiveness of these suggestions and what recommendations you would make to cure our damp problem. We thank you in advance for any help you can give us.

 

[ree]

Pics would help.
Internal and external pics, and any pic or sketch of the exposed interior framing.

Typically, a DPC or membrane wrapping is necessary to protect the sole plate against rising or penetrating damp - however, when the framing is embedded in the cob its at risk of moisture penetration from all directions.

Slipping a DPC below the plate might help solve the difficulty but without pics its difficult to say.

You might have damp rising from the brick floor and/or damp rising up through the cob? But it might be penetrating damp coming in above the plinth and plate line?

How high above the exterior ground level is your interior brick floor?

I could comment on your options but until pics arrive my mental picture of the site conditions are a bit unclear.

 

[keithsh]

Thank you for your very quick response ree. Pictures now attached. With respect to the walls one is taken inside a cupboard where the damp is worse and the other is taken of the same wall but on the other side of the cupboard where the wall looks in much better shape but where there is damp between the top of the wall and the beam. The exterior picture shows where we have begun to scrape off the paint to make the wall more breathable. The interior floor is about 30cms above the external ground level. Thank you.

(I have added pictures to an album as prompted but they do not seem to be attached to this message.)

 

[keithsh]

Hopefully you can see the pictures in this post if you cannot see them in the previous one.

 

[keithsh]

Apologies if you cannot see the pictures I posted. If you cannot see them then you might be able to access them at //www.diynot.com/network/keithsh/albums/

 

[ree]

The brick flooring in the cupboard is blowing, and one way or another it should be lifted and re-laid with a membrane below the brickwork.

However, there is an oak balk (previously used as a wall plate) now being used as a step into the old pantry(?).
Strictly speaking, that too should be lifted and the membrane extended below the step - but its your call.

The seven or so courses of brick work could be removed and replaced with new brick on a concrete footing- blue brick is best but its not in keeping with the cottage - and a DPC inserted at low level.
After the inner plinth brickwork has settled, it might pay to remove the outside plinth brickwork and replace with new brick, on a foundation concrete footing and a DPC.

Further along the wall, below the window, the brickwork to the wall plinth appears to have been replaced with newer brick.

The floor may have been re-layed at some past time, without, probably, any membrane

Pitch and liquid bitumen and paint has been applied to the outside plinth to help prevent damp penetration.

What i've suggested above probably sounds extensive but its a very basic schedule. There's much more detail but for now you have something to think about.

If your cottage is listed then all bets are off. But its obvious that "recent" works have taken place.

The difficulty is in maintaining an old building with modern practices and materials. Only you, the keepers of the flame can make the calls.

 

[ree]

Options:

1. Dryline and skim - means merely covering up the ongoing problems. Plus the possibility is that the Dryline adhesive will fail on a damp wall. Dryline (aka dot and dab) is totally out of character with the cottage, and might bring on further difficulties.

2. Pump "breathable sealant" - into what, the bricks, the cob, the plate? Sounds like Damp and Timber company salesmen nonsense. Specific names of proposed materials would be required.

3. The moisture is coming from below and from the side, and from above in all probability. A DPC below the plate can only help when its installed in conjunction with other remedies.

4. Membrane under which floor?
There are no indications that the wall(s) was previously lime plastered. In your case i dont think it would help.

 

[ban-all-sheds]

Apologies if you cannot see the pictures I posted. If you cannot see them then you might be able to access them at //www.diynot.com/network/keithsh/albums/[/QUOTE]

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[keithsh]

Thank you again ree. We have spoken to our builder of choice and he is going to sort the exterior wall out - initially making it breathable again and repairing the wall/replacing the bricks as appropriate. He has suggested putting in an air brick in the cupboard, not that it is "compatible" with the cottage but because it is practical to do so, to get the air circulating. He is also going to put a layer of slate under the penultimate row of bricks. He has also suggested putting in a French drain, 5 metres or so from the external wall - the garden/land slopes towards that corner of the cottage and it is this which he thinks the damp has come from. He suggests putting a clay "collar" at the bottom of the wall to protect the clay at foundation level from drying out with, I think, shingle above this. This will keep the wall "healthily damp". Any excess water will drain away to the French drain. Although the floor does need relaying in the cupboard I think the idea is to see if the work suggested will sort out the damp in the cupboard floor before doing anything with the floor. Does this make sense to you? Best wishes.