Damp course (lack of!)

[twobecks]

Hi all,

Does anyone have experience of applying DPC to their build?

I have made the structure of my WFO out of breeze blocks, but didn't even think about laying a damp course. Now as I want to render the outside for a finish, I am worried about moisture rising from ground level through capillary action which may damage the render over time.

I've looked around and found this product: www.twistfix.co.uk/products/damp-proofing-cream/diy-damp-proof-cream-dampcure-380-dpc-product.html

Has anybody used it? The manufacturers say to apply this 150mm from ground level directly into the mortar bed. It will only proof on the course which it is applied, so I am worried that the lowest course won't be protected and might cause any render applied to become loose through damp over time.

I am very keen to hear of any other methods to achieve the same outcome - a waterproof seal from the ground!

[DuncanM]

Hi twobecks,

I used a DPC in my construction, which, like yours was laid with a concrete block base:

ukwoodfiredovenforum.proboards.com/index.cgi?board=bvovens&action=display&thread=136&page=2

I'm glad I did because I saw moisture rise through the first course after I'd constructed it, and it did did at the DPC.

No experience with render so someone else will have to help you out there I'm afraid.

[turkey]

I have thought about this but I rendered in bricks so seems externally ok.

I also failed to place any membrane under the base slab when cast.....

I was thinking about drilling some holes in the block work to allow air flow, partly to keep the blocks dry but to also make sure wood stored there could stay dry or season depending on what I buy etc....

good to see some ideas regarding this as I did not even think of it when building as I am not a builder .

[twobecks]

Thanks for the feedback.

I really should have considered this, given the amount of planning that went into everything else. I think I'm going with a plan along the lines of Turkey's where I'll create some vents on the rear of the base blockwork for air circulation. Once rendered, I'll fit nice vent plates to cover the holes.

I'm probably going down the drilling/injecting the liquid damp proofer road as well. It doesn't seem too expensive, and I don't want to be repairing blown render a year after the build is finished.

I'll update my build photos and descriptions when I do it, and report back on how successful it is.

[cannyfradock]

Twobecks

How far are you with your build? As a bricklayer I always lay a DPC when building blockwork/brickwork. If you have yet to pour your slab ...or lay lintels to hold the sub base for your hearth, then you could incorporate a dpc between walls and slab.

Silicone injection works great, but it's an added expense......

Terry

[twobecks]

Hi Terry,

Unfortunately, the slab is laid and the dome is on. I only realised my monumental screw up when the blockwork of the structure started to soak up the rain like a sponge.

Silicone injection it is then!

[tapir]

My BVO is supported by hollow concrete blocks, filled with concrete. I've not installed a DPC, probably should have done now.

The blocks will be protected from the elements by a brick course (ironically when it stops raining, I can get out and make a start on this). The wood store will be open to the air, so I'm planning on painting some waterproofing bitumen paint onto these. any thoughts on this? I'll probably be sticking a door on the front too, but need to still maintain some airflow in there.

As for the external brick course - I'll certainly add a DPC 2 or 3 courses up