Rising Damp in 1850's tenement - Resin DPC

euan_

Hi all,

I'm looking at buying a ground floor tenement flat, build circa 1850's with stone wall construction. There are damp issues, and some remedial works have been done to install cavity drains behind some of the worst walls, however, I suspect the building has no DPC (they weren't always used pre 1860's, I believe) so any damp will continue to rise up the walls, and the cavity drains wont be addressing the root of the problem.

Does anyone have experience with the effectiveness of resin injection dpc into stone wall buildings (probably 600mm thick walls) - and if so, what are the approximate ballpark per metre costs I should be looking at.

Having inspected the property, the solum is only about 2-6inch deep below the joists, and the vents are partially blocked by rising ground levels to the front. Do you think unblocking vents, lowering the ground level and installing some form of low volume mechanical venting in the solum would limit the issue? Walls are dampest to the blocked side of the building.

Finally, is this flat ever going to be dry, or should some damp, regardless of how much money gets thrown at it, always be expected with buildings of this age?]


Cheers
Euan

buglawton

See http://www.heritage-house.org/the-fraud-of-rising-damp.html first

G_M

Slate was commonly used in old houses as a dpc. I have it (1851 property). You won't see it from outside. Lift a floorboard.

Injecting stone walls? :eek: The only people who will recommend this are the[STRIKE] salesmen[/STRIKE] 'surveyors' providing a free damp survey on behalf of..... a damp-proofing company that does resin injection.

Rising damp is vastly over-diagnosed. Damp usually originates elsewhere.

Blocked vents? Unblock them! Get a good airflow. It'll dry everything out (over 3 - 6 months). Sorted.

Rising ground level? Breaching the (slate) dpc.... ? There's your problem. Extract a channel around the exterior walls reducing the exterior ground level. Sorted.

euan_

@G_M
Thanks for the advice - it echoes my gut feeling over resin injection (In my head, I just couldn't see it working that well in a wall of this type.)

I do think the answer will lie in dropping the external ground and increasing ventilation - which is also the cheapest solution, so the one to try first! I may even install mechanical assistance in the form of a ducted dehumidifier for 6 months the speed up the process.

My thoughts were to dig out approx 450mm and refill with 150mm gravel (creating 300mm difference between grade/FFL) - is it worth applying bitumen paint to the exterior wall 150 above grade to inhibit some passage of water inwards?

Additionally, if I was planning on insulating the floor, would I be best using a thin foil based product over the joists to avoid reducing the airspace below? (Or a combination of foil based over, and 50mm PIR between). I'm aware I don't want to block airflow beneath - and I'm thinking insulating potentially reduces condensation in the solum, and again might help alleviate the amount of water vapour present.


Any thoughts appreciated, cheers
Euan

buglawton

Isn't another myth about damp that it can 'rise' through brick?

Now, moisture can rise through a porous material, true, via capillary/wicking action. but with an old brick wall sitting in normal moist earth but allowed to breathe, damp will not actually rise very much.

So yes, concentrate on ventilation is the right thing.