Black Jack before Dot n Dab???

macadonald · 25 Oct 2010

Hi Guys,

Just taken all the plaster off of the walls in our box room and was planing to dot n dab plaster board onto the brickwork instead of render and plaster again. Makes life much easier for a diyer. No sign of damp comming through, but once I've cleaned the brickwork as best as possible and applied a coat of PVA, could I paint the bricks with black jack, throw on sharp sand and then dot n dab? I don't really like using black jack (messy and permenant), so if there is another type of sealant, please let me know.

Also, a assume I can use a slightly thicker insulated plaster board on the outside facing walls, rather than render. I think I've seen plaster board with a moisture barrier, insulation and plaster all in one. Not sure how thick this is though?

Thanks

Alastairreid · 25 Oct 2010

why do you want to paint the walls with tar if they are dry/damp free?

macadonald · 25 Oct 2010

Simply long term precaution, but you're right, if I don't need to I won't.. So insulated plaster board onto brickwork (dot n dab)?

Alastairreid · 25 Oct 2010

d&d insulated plasterboard directly to the masonry using board adhesive.

plstering · 25 Oct 2010

as m8ty said

joe-90 · 25 Oct 2010

Being as this thread seems finished - can you use Blackjack for tanking in bathrooms before tiling?

WabbitPoo · 25 Oct 2010

macadonald said:
Hi Guys,

Just taken all the plaster off of the walls in our box room and was planing to dot n dab plaster board onto the brickwork instead of render and plaster again. Makes life much easier for a diyer. No sign of damp comming through, but once I've cleaned the brickwork as best as possible and applied a coat of PVA, could I paint the bricks with black jack, throw on sharp sand and then dot n dab? I don't really like using black jack (messy and permenant), so if there is another type of sealant, please let me know.

Also, a assume I can use a slightly thicker insulated plaster board on the outside facing walls, rather than render. I think I've seen plaster board with a moisture barrier, insulation and plaster all in one. Not sure how thick this is though?

Thanks

why the pva?

joinerjohn · 25 Oct 2010

WabbitPoo said:
why the pva?

That's because every DIY'er knows the benefits of that exotic white plastic based liquid. It's a cure all panacea. didn't you know?

Richard C · 25 Oct 2010

joe-90 said:
Being as this thread seems finished - can you use Blackjack for tanking in bathrooms before tiling?

Wasn’t sure if your post on a previous tiling thread was a serious question or not; but for what it’s worth, here’s my view.

Don’t have much experience with Blackjack other than references but I understand it’s similar/same as Synthaprufe Aquaseal which I have used a few times in the past. I’ve never tried tiling over it but don’t think I would risk it. I can’t imagine the bond strength would be that good &, depending on the size of tiles, they may move around or even end up on the floor; assuming it’s not a floor your tiling! Why do you want to use Blackjack instead of a proprietary tanking liquid or even membrane tanking?

joe-90 · 25 Oct 2010

Cost.

Richard C · 25 Oct 2010

joe-90 said:
Cost.

Thought as much

but it can cost an awful lot more if it all goes T/U.

macadonald · 25 Oct 2010

joinerjohn said:
WabbitPoo said:

why the pva?

Click to expand...

That's because every DIY'er knows the benefits of that exotic white plastic based liquid. It's a cure all panacea. didn't you know?

I get ther sarcasm and not denying the diyer I am

You experts suggesting I don't use pva? I understood that it was good as a sealer to rough, loose or dusty surfaces. Have I got this wrong?

memor maplin · 15 Dec 2010

Older buildings are meant to breath they take in water and let it out when it's dry. If you start painting the walls with black Jack it stops them from doing this.
Condensation that would be sucked into the walls condensces on them instead and has a go at the joists. This is what has happened to me and my floor sagged because the joists in the walls got extra wet due to black Jack.
There are rendering slurries on the market for damp cellars which keep water out and still let the walls breath.

As a new floor cost me close on a thousand pounds try and avoid black jack if you can.

Shewie · 1 Jun 2011

Hi,

First time on here so not sure if using right. You guys could have the answer to what i've been searching for.

I have a chalk wall (plus the odd bit old as brickwork) cellar that needs tanking out. I would like if at all possible to use a clear version of a ''Black Jack'' type agent so I can retain the chalk facing (rather than boarding over).

Is there such a product that you know of that will provide a damp sealant but can keep the chalk facing?

Thanks ever so in advance

**also seeing Memors comments about avoiding black jack to keep the porous chalk breathing is of equal importance in getting the right clear agent if poss.**

Shewie.

freddiemercurystwin · 2 Jun 2011

Retaining the internal existing finishes on cellar conversions that suffer from damp is only possible by tanking on the outside.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Black Jack before Dot n Dab???

plstering

joinerjohn

Similar threads