Drilling into damp proof membrane

[kevin_robson]

I am in the process of building a stud partiton wall. It is to block up french doors in what was once a solid brick wall on ground floor.

I will be drilling and screwing the lower beam of the wall frame into bricks at ground level, which already have a damp proof membrane on them. I will also be putting a DPM directly underneath my woorden beam in case the original is knackered.

Presumabely by screwing through damp proof membrane it ceases to be damp proof? How do I get around this - I wondered about putting silicaone sealant around the hole in the damp proof membrane? Or does it not really matter?

Thanks

 

[Softus]

Your primary objective here should be to provide a contiguous layer of DPC, i.e. one in the wall that overlaps with the one covering the oversight of the floor. This is because moisture finds it much easier to climb through a narrow gap than through brickwork, by virtue of capillary action.

BTW, don't get duped by proponents of the idea that moisture can rise through courses of brickwork by capillary action - this is a myth.

So, whilst I'd try to avoid puncturing the DPC at the base of the wall, you're going to have to if you insist on using timber and screwing it down.

Is there a particular reason that you aren't bricking up the old doorway? Obviously you'd need to tie it in with the existing walls, at the sides, but this would avoid puncturing the DPC.

 

[kevin_robson]

I'm building a stud wall purely as it will be easier and quicker for a DIYer. I dont fancy the idea of bricking it up.

My other option would be to anchor the frame at the sides only, and maybe at the top if I can drill into the RSJ - see my other posts on this one. Is that likely to be an option - I suppose in theory there shouldn't be alot of need to anchor a beam of wood to the floor, as it should pretty much stay there anyway.

Thanks

 

[Softus]

I'm building a stud wall purely as it will be easier and quicker for a DIYer. I dont fancy the idea of bricking it up.

IMHO, bricking up a hole is simpler, easier, quicker, and requires few tools, than making a studwork wall in the gap. You could use concrete (or aircrete) blocks for additional speed and ease.

My other option would be to anchor the frame at the sides only, and maybe at the top if I can drill into the RSJ - see my other posts on this one. Is that likely to be an option - I suppose in theory there shouldn't be alot of need to anchor a beam of wood to the floor, as it should pretty much stay there anyway.

True, but it will still transmit more noise that a masonry wall, and you can't hang stuff off it so easily.

 

[kevin_robson]

Thanks For your advice, even if I am about to ignore it!

I'm afraid I'm gonna have to stick to a partition wall. I've never laid bricks in my life, and dont really have the time to learn at the moment. Need this build before the weekend.

Looks like I'm going to include some acoustic mineral wool to try to help with the sound insulation a little. I'm assuming it will be OK as newbuild houses are all partition walls anyway.

Going back to the original question, what is the best option : drill into the damp proof membrane anyway or just support the wall at the sides only? If I go through the DPM is using sealant of any use whatsoever?

Thanks

 

[samsung]

I must agree with softus. A brickwall would be a lot better than a stud wall, as I found out when I took a window out and this london builders told me after I did a DIY job on it myself first and the noise you could hear through the stud wall was unreal, when he built my house extention .

 

[Softus]

Thanks For your advice, even if I am about to ignore it!

At least you're honest.

Looks like I'm going to include some acoustic mineral wool to try to help with the sound insulation a little. I'm assuming it will be OK as newbuild houses are all partition walls anyway.

And you think that newbuilds are OK?!

Going back to the original question, what is the best option : drill into the damp proof membrane anyway or just support the wall at the sides only?

For strength I would drill and screw it in downwards, but then again I wouldn't be building a stud wall.

If I go through the DPM is using sealant of any use whatsoever?

Yes - use Dow Corning 785 clear (or anything mildew resistant of similarly top quality), and don't let it start going off before you put the timber in place or it will stand proud.

 

[wilgartw]

just a thought, and i am a novice, but why not put down a single layer of bricks and then drill into them. best of both worlds!

 

[ABN]

"It is to block up french doors"

Is this an internal or external wall ?

As a devout bodger what springs to my mind is thus.
The width of french door is quite a bit and if the stud wall is not fixed at the bottom it would tend flex rather a lot. So wrap the bottom member of the stud with the damp course then fix a non porous batten to the floor either side of it. That would stop the flexing no need to fix the stud to the floor as there shouldn't be and vertical movement.

But if it is an external wall should you be using a stud partion?

 

[kevin_robson]

Its internal.
I've anchored the frame at the sides and top, and the bottom doesn't seem to move at all. Will see what happens when the boards are attached but I'm confident it should be OK.

Thanks all.

 

[WabbitPoo]

just a thought, and i am a novice, but why not put down a single layer of bricks and then drill into them. best of both worlds!

Nice lateral thinking there mate! Like it, though have no idea if its Ok to do it!

 

[kevin_robson]

"The width of french door is quite a bit and if the stud wall is not fixed at the bottom it would tend flex rather a lot. So wrap the bottom member of the stud with the damp course then fix a non porous batten to the floor either side of it. That would stop the flexing no need to fix the stud to the floor as there shouldn't be and vertical movement"

What do you mean by 'non-pourus'.
Sorry, obviously I know what you mean, but do you mean wood or what? I think I might try to support it a bit from lateral movement and reckon I can wedge it in using a strip of wood. Is wood termed non-pourus? I'll put it on a thin strip of DPM anyway either way.

Cheers

 

[Softus]

I've never read such a load of old nonsense!

As for laying a single course of bricks with no weight on top of it and expecting it to stay in place - I'm lost for words. Do the people making these suggestions have the first shred of experience?

Bottom line - as ABN pointed out, if the bottom member isn't fixed in place then it WILL flex. Are you hoping to skim the finished wall with a coat of plaster and have it not crack? No chance.

kevin_robson - with the amount of thought you've put into this you could easily have learned to mix the three components of mortar, and with the time spent posting on the topic you could have whacked up a breeze block wall.

It's not too late...

 

[kevin_robson]

Softus,
A few questions:
Assuming I did decide to have a go at this, what would the cost in breeze blocks be for a 2.4M * 2M wall?

What mixes do I need for the mortar?

Does the wall have to be joined to the rest of the wall with anything other than just mortar i.e. does it have to be keyed in or held by ties, or is mortar and gravity enough?

Is it easy enought to cut a breeze block to make up the interlocking pattern?

Thanks

 

[Softus]

Softus,
A few questions:
Assuming I did decide to have a go at this, what would the cost in breeze blocks be for a 2.4M * 2M wall?

Blimey - I dunno. I'd have to work it out; or you could ask your nearest builders' merchant the same question...

What mixes do I need for the mortar?[/quote]
3:1 sand:cement, then add water to make a workable consistency. Your first mix is likely to be too watery.

Does the wall have to be joined to the rest of the wall with anything other than just mortar i.e. does it have to be keyed in or held by ties, or is mortar and gravity enough?

You could chop it in, but ties are much easier and quicker. Alternate course would be strong enough.

Is it easy enought to cut a breeze block to make up the interlocking pattern?

Yes - especially aircrete, which break up if you just show them the words "hammer and bolster".