Damp membrane help please.

[Graemevw]

Ive started laying the blocks for my garage but am now unsure if my plan is ok.

Its not 100% a garage, will be general workshop so im trying to get it snug and dry.

One short wall with the opening has floor just above outside ground level, but all other 3 walls have ground level 4 blocks up from internal floor.

I was going to put dpc here, then bring the membrane up the internal walls and lap it into the dpc.

However, i keep thinking about it and im not so sure this is wise. There will be a few foot of exposed membrane up the internal walls, i was going to board over this somehow to protect it, but im not sure about laying the membrane all around the piers etc.

Ive not done this before.

Will it all work out fine? Just cut where needed, patch where needed and join it all with tape?

Or, should i be putting the dpc low down, laying the membrane into that, then putting a second dpc higher up and sealing the walls internaly with a rubber damp paint?

Cant seal walls externaly as ive not dug enough clearance. Dont want to just lay membrane up the external walls, doesnt seem right.

Ive already built 2 corners and one short wall up to my origional high dpc level unfortunately but could cut some mortar out and tuck membrane in.

How should i tackle this?

 

[noseall]

If you fit a vertical dpm then you will need to add a second skin to protect it, surely?

 

[Graemevw]

As i say, was going to board the lower half of the walls to protect membrane, fixed into walls above the membrane.
Not sure how i'd fix the bottoms but i'd sort something.

Fair bit of faff boarding all round the piers though.

Its the awkwardness of laying the membrane up all the walls, and round all the piers, then boarding thats made me think maybe im not on the right track with my plan.

What do you think of putting in a low dpc, putting the membrane low too, then putting a high dpc above external ground level and using rubber paint inside between the 2?

 

[^woody^]

Coating the inner wall may work, but there is the risk of it being blown off by the water coming through. Its not ideal

If you run a DMP up the inner wall then yes you need to protect it with timber board or something

Or have a look at this or some sort of variation

Run a vertical DPM up the external wall and lap this with the DM under the floor. The timber board will protect the DPM, and a lead (or flashband) cover will protect the DPM out of the ground

Untitled

• ^woody^
• 6 Jul 2012
• 1

Edit:

Potentially, the DPM could be tucked in at ground level and then two course of blue bricks could be used above ground level instead of the lead

 

[Graemevw]

Nice idea, but would mean taking down the wall ive already built.

Im not super convinced about coating either, any movement in the walls, cracks etc, and it will be broken. Getting it in all the little nooks on the concrete blocks may also be tricky.

Maybe ill have to stick to what i was thinking.

 

[Graemevw]

Been checking levels and i may need to go higher before the damp course, 5.5 blocks above floor so 6 blocks from membrane to dpc.

I figure to make things easier can i just lay the under floor membrane 1-2 foot up the wall, then run the piece up the wall seperate and tape it to the floor membrane?

How much can i chop the membrane about and tape it back together, is it important to have as few seams as possible?
I assume there is special tape? Ive not looked yet.