Fixing through the DPC

[nsreglj]

I'm planning to install a section of fully insulated timber framed wall to replace an uninsulated single leaf brick wall. I've a solid concrete floor, so fixing to to the floor will require the screws/plus to go through the DPC. When I spoke to the local building control office they said that is possible and I'd need to used a bitumen based product to "seal the holes".

I've searched the internet, and come up with a number of liquid DPC products which woudl seem to do what I need. I'm looking for suggestions as to the best way of actually doing this that will satisfy building control.

Thanks for your help
Nigel

 

[noseall]

I'm planning to install a section of fully insulated timber framed wall to replace an uninsulated single leaf brick wall. I've a solid concrete floor, so fixing to to the floor will require the screws/plus to go through the DPC.

Why will it mean puncturing the damp proof layer?

I take it that by fixing to the floor you are referring to the dpm and not the dpc?

 

[Richard C]

You don't need an expensive tin of liquid membrane, use any bitumen or mastic based gun sealer on the screw threads & a big blob under the sole plate around the holes; silicone sealer will also work.

A bit of an over-reaction by LABC I think but technically correct. Don't worry it will be fine & unless it's near an exterior wall or you have a high water table, there will be very little moisture under the DPM anyway, let alone enough to work it’s way up past a few screw threads!

 

[nsreglj]

I'm pretty sure that it is the DPC and not the DPM. What I want to replace is a large window/door frame that makes up most of the back wall of the ground floor of the house (built in the late 60s). At some point in the past somebody has removed a bit of the lower part of the frame and bricked it in with a single layer. As far as I can tell this all sits on the DPC, and is in effect the exterior wall.

Richard, I'd thought that a bitumen mastic (like the stuff used for repairing roofs?) would do, but when I asked the BCO they said I should be looking at the sort of thing used for tanking basements. A liquid DPM is the best thing I've managed to come up with so far.

What I was thinking of doing is dipping the plugs into the liquid DPM and letting them dry with a layer on, then putting them into the holes with more liquid DPM, and dipping the screws as well before fixing the sole pate down.

Thanks
Nigel

 

[Richard C]

I'm planning to install a section of fully insulated timber framed wall to replace an uninsulated single leaf brick wall.

I think you need to explain more exactly what it is you’re doing here; I’m just a little confused as I thought you were talking about an internal stud wall but am getting the impression it’s a little more involed than that!

 

[nsreglj]

Richard,

Sorry, I'm not making things very clear. Its not an internal wall.

I have a combined single glazed window/door frame at the back of my house which extends from the floor to within a foot or so of the ceiling. The whole lot sits on the DPC above the concrete floor/base. I want to replace it, and replace the lower portion of the window area with a timber framed wall. This will need to be secured to the concrete base, which will involve penetrating the DPC. I'm trying to find a way of doing this which will satisfy building control, who seemed to imply that it was possible.

Perhaps it isn't, and it more complicated than I imagined

Nigel

 

[noseall]

Why not build a masonry wall then fix insulation to the wall?

 

[Richard C]

Perhaps it isn't, and it more complicated than I imagined

It's not complicated & I'm not really sure what LABC's problem is; perhaps the tea lady is dealing with it! As I said before, any proprietary sealer around the screws & screw hole will suffice to hold moisture penetration at bay but if the LABC tea lady really wants a liquid DPC then use that; I’ve always used Synthaprufe
http://www.ruberoid.co.uk/pages/rub...product_page/default.aspx?CatID=57&ProdID=161

buying a whole tub may be a bit expensive but if it satisfies LABC