Wine cellar butyl liners, and gluing to the DPM?

[mkilpatr]

Hello all,

we had a wine cellar (floor hatch) built into our new utility room as part of the extension - except that the builders got it wrong and tried to use something completely inappropriate to waterproof it: a paint-on bitumen emulsion which is only good for damp-proofing, not underground hydrostatic pressure. We need a proper membrane or impermeable solid construction.

The best solution would have been a rigid polypropylene box built-in before the utility room was constructed above it, but it's a bit late for that unless we dig out a little bit of the floor screed, slab, etc.

Anyway, one solution is to make a box-welded butyl liner to drop in. Plenty of companies can do that for us. But I really need to know exactly how best to weld this to the edge of the main DPM to make the best all-round waterproofing. I want to eliminate the possibility of capillary action between the two mating membranes allowing water to creep up, over and into the cellar.

Anyone know much about the sorts of tapes and adhesives that could be used in this situation?

The construction is as follows:

The cellar has a base slab and an outer skin of blocks. The cellar cavity is about 1.7m x 1.2m and only 0.7m deep below the room's DMP and slab. After the cellar DPC is installed there will be a screed slab and an inner skin of blocks, atop which will sit the framework for the hatches. I'm not going to tile or paint it, so the cellar will just be bare block walls and screed base, with wine racks plonked inside and screwed down if necessary.

The hatch and inner blockwork have now been demolished thanks to the useful damp-proof stuff the builders used so we can start again with a waterproofing that actually works before rebuilding it.

think I need to be sure of the best way to adhere a liner to the exposed edges of the DPM around the hole so as to get the best all-round watertight seal - if indeed that is necessary. There are only three inches of the main damp proof membrane protruding around the edge of the cellar cavity. As the base slab, insulation and screed of the utility room have all been laid, exposing more of the DPM would require some breaking-in.

I'm also wondering if, when using a butyl liner, we should break a drain hole through the cellar base slab to prevent water pooling under liner and trying to float it and the screed floor inside it! With only 0.7m depth below DPM I can't see that much pressure building up, but you never know. Any thoughts?

Michael

 

[ReggieStrant]

Hi,

I'm wondering whether a quick cross-sectional sketch of your hatch-cellar / DPM / screed might inspire others to answer?

 

[mkilpatr]

Hi,

I'm wondering whether a quick cross-sectional sketch of your hatch-cellar / DPM / screed might inspire others to answer?

Perhaps I might have time to try to upload a sketch tomorrow. But it's fairly straightforward. The utility room comprises DPM, base slab, insulation, floor screed in that order. The inner vertical faces of the outer walls of the cellar are flush with the edges of the slab/insulation/screed of the room, and the DPM was cut to stick out a couple of inches (except at the corners, of course).

Top of cellar base slab is about 0.65m below room DPM.


Michael

 

[RedHerring2]

I always thought that wine cellars need to have a high humidity level, so a damp free area is not absolutely necessary.

http://en.wikipedia.org/wiki/Wine_cellar

explains the difference between passive & active wine cellars.
Yours will be a passive wine cellar ( I assume) so there's no need to go overboard with damp-proofing. (excuse the pun)

 

[r896neo]

I did this recently with a lift shaft in a new build house which was effectively the same idea but on a bigger scale. Your concern that hydrostatic pressure could float the butly is valid, but only if you are significantly below ground average ground level. i.e you live at the base of a hill or your house is terraced into a hilside. This was our situation so we put a concrete base in built a blockwork shell, fitted the butyl liner then poured another concrete base and built the butly in with another layer of blockwork.

Of course you may not have the room to sacrifice to do this.

As for sealing to the floor dpm just use denso tape

 

[mkilpatr]

I did this recently with a lift shaft in a new build house which was effectively the same idea but on a bigger scale. Your concern that hydrostatic pressure could float the butly is valid, but only if you are significantly below ground average ground level. i.e you live at the base of a hill or your house is terraced into a hilside. This was our situation so we put a concrete base in built a blockwork shell, fitted the butyl liner then poured another concrete base and built the butly in with another layer of blockwork.

Of course you may not have the room to sacrifice to do this

Thanks. That is exactly how the construction was intended to be anyway, except we had the wrong sort of damp-proofing. The inner blockwork has been demolished pending finding the correct DPC. So no, we won't be losing any space when we build inside a butyl liner.

The base of the butyl liner would be 70cm below the DPC of the room. That's not at all deep. Do you think a concrete base above the liner 50mm deep would be fine to prevent floating/cracking?

We're on pretty flat ground - Whittlesford, South Cambs. There appears to be little or not groundwater but we're baffled by dampness that was soaking up the through the base slab and the bottom of the outer walls of block.

We had a rain harvester tank sunk into the front garden. A hole 3mx3mx3m was dug for it. Not a drop of water gathered in the bottom.

 

[r896neo]

In that case I don't think there will be much pressure at all, because our lift shaft was 1.4m below the footings and we had excavated 4m below the original ground level and to terrace into the hill-side. To top it off the hill continued above us for another mile but it's a golf course.

As for the base, anything would be fine for holding it down so 50-75mm would be plenty.

The dampness is probably largely caused because the rest of the floor is under an impervious sheet i.e. the dpm. The moisture gathering under it migrates along and into the cellar as it is a natural sump. I doubt it's ground water in the conventional sense but rather the condensing effect caused by the complete barrier to natural water movement and evapouration in the form of the dpm.