Dot and Dab

[sweeneyuk]

I am renovating my 1900 terraced house & would be grateful for some expert advise.

The origanal plaster was well shot & falling away in lumps exposing the brickwork on the front external wall.

this is a solid wall with my front door & 1 window.

I want to dot & dab plaster board to ease decoration but have a few questions for all you experts.

1. when using tapered edge plasterboard how to you join & fill the non tapered edge if you only plan to tape & fill the tapered edges?
I see the american/canadian diy shows never plaster their drywall, just fill the joins & screwholes.

2. Will i need to use a foil backed board as its an external solid wall?
no damp issues but have some exposed brickwork.

3. as the plaster has been patched in places in the past i have a very uneven surface to work off. the are areas with render, plaster & some with bare brick. can i just add extra adhesive when dotting & dabbing to bring it all level?

If i was to use insulation backed board like celotex pl3000 will the insulation react with the pvc insulation around electric cables?
Should they just be capped?

Also just a word of warning, steer well clear of crystal double glazing, long story for another post.

Any help appreciated.

 

[PrenticeBoyofDerry]

You try not to but up square edge with tapered, but can feather the joints out, if you dot'n'dabbing no real reason why this should happen, foil back boards will help reduce condensation, but if no issue, should be okay.
I'd knock off all the existing plaster down to bare walls, the foam insulation should not effect the cables. Polystyrene does and if the cable are total surrounded by insulation that will, but that again will not be an issue.
The joint taping method, if done as a novice can look poor, and is not as durable as a plaster finish, so consider that as it can be done in one hit and joint taping needs three applications and three sanding downs.

 

[sweeneyuk]

Thanks pbd,

How do i avoid the non tapered edges?

My ceilings are 2.6m & the boards only 2.4m so if i have them vertical i'll have a non tapered edge near top & bottoms & if i run them horizontal the non tapered edged will be between every board.

how are you meant to avoid having the square edges anywhere other than the corners etc?

Is the celotex pl3000 a foam back?

any recommendations for boards with 25mm of insulation?

trying to avoid removing the rest of the plaster as some is a concrete render & pulling the brick work apart.
can i just add more dot & dab to the deep areas & less to the shallow?

 

[jrplastering]

sorry did you say you was dot and dabbing foil backed boards?
this is a no no im afraid the dot and dab wnt take to the foil and it will come away

 

[roughcaster]

sorry did you say you was dot and dabbing foil backed boards?
this is a no no im afraid the dot and dab wnt take to the foil and it will come away

Well spotted JR!!

 

[sweeneyuk]

not bought any boards yet just trying to work out best way to go about finishing this wall?

If its a solid external brickwall & i plaster board will the cavity between the boards & cold solid wall cause moisture to form & eventually mould?
Or would this only happen if damp was already an issue?
no damp or sweating at all.

Trying to avoid battening as the wall is so uneven where the plaster has fallen away & been repaired in patches over the years. these patches are all different materials, some cement, some a kind of very hard plaster but all incredibly difficult to remove without pulling the soft old stock bricks away with it.
not to mention the incredible amount of dust causing my knackered lungs no end of greif! also pulled all the ceilings & skirting, chased in new sockets during rewire & removed a partition wall, got wife pregnant & need to get house normal again asap!

Want to dot & dab as i thought maybe i could just add more or less adhesive to level the boards?

Also thought using an insulated board might be a good idea as the wall is solid.

although i woild like the easiest & cheapest option that will still not cause any issues.

What would an expert do?

 

[sweeneyuk]

Okay i have started to remove all the plaster & render back to brickwork much to my wife annoyonce!

Now do i batten the wall or build a stud wall?

If i build a stud wall how far away from brickwork do i build it to allow air gap?
do i treat the brickwork 1st?
will having heating pipework/ cables in the void be ok?

If i batten the:

Should i batten it with 2x1 battens with insulation inbetween, vapour barrier & then plasterboard?

If so do i run battens horizontal or vertical?
Should i treat the brickwork with anything 1st?
should i use treated 2x1?

worried about losing too much of the room as it only a small terraced house.

Also when screwing a studwall base plank to a concrete floor what kind of gasket should i use as i have had trouble locating 1?

 

[PrenticeBoyofDerry]

Have you thought about using metal stud.
http://www.british-gypsum.com/products/gypframe_metal_products.aspx
If you leave about 50mm behind the stud(timber or metal), you can install insulation behind it.

 

[Richard C]

Also have a look at these;
http://www.british-gypsum.com/produ...es/gyproc_thermal/gyproc_thermaline_plus.aspx
they provide additional insulation & have an integral vapour barrier, ideal for old solid, walls.

Be careful when removing all the plaster/render back to brickwork on outside walls; if you remove more than 24%, Building Regulations require you to upgrade the thermal insulation to current standards. Getting caught out can easily happen if your having a Building Inspector look at other work your doing & then you will have additional & unexpected work/expense.

 

[sweeneyuk]

so if i want to use thermaline plus can i batten direct to brickwork & boards on?

really want to avoid building stud wall in front of brickwall as there is too little room to lose any more.

Also whats best, cheapest & easiest way to protect electrical cables if using a polystyrene backed board as it will react with the pvc sheath on the cables?

thanks for the help.

 

[Richard C]

You can fix using battens or use direct fixing; British Gypsum seem to have produced a brand new guide which looks better then their original, have a read & come back with more questions if you need;
http://www.british-gypsum.com/pdf/LIT_InstallationGuide_02.pdf

As far as polystyrene reaction with cable insulation, I would contact BG for clarification as the styrene they use is both CFC and HCFC-free which may be relevant. If not, plastic conduit or capping is probably the easiest solution, observing safe zones of course.

 

[sweeneyuk]

cheers,

Have been looking at the link & think gypliner universal might be best bet.

Have been trying to remove all the old plaster today & is pulling away too much wall with it, esp around base of door & window.

Also window reveals are not square from inside to out, the inner wall is stepped back by 75mm & partially been squared with plaster.

so removing all the old is a no go.

would i be right to think i could use the gypliner universal, find the high spot on the wall (obviously will be a part thats still got the old plaster on) then build the gypliner wall from this high point?

If not will i need to leave a gap between the gypliner & the highest point so its say 10mm away at high spot & prob 50mm at lowest where i have removed plaster?

do i install insulation between the metal studs and/or use thermaline boards?

cheers

 

[PrenticeBoyofDerry]

polyurethane is okay and should not react with PVC cables, it's polystyrene that does, there is a reaction called marring, that effects the plasticizer in the PVC, this cause the cable to go brittle.
The other effect insulation can have is if the cable is surrounded by insulation, the cable will then not be allowed to disipate heat, this will cause the cable to over heat. If this is a factor, the cable may need upgrading to a larger CSA.

 

[Richard C]

I’ve never used Gypliner Universal personally but your going to have to provide a plumb & level base to fix it to so the stand off brackets or packers would fit the bill. If your using Thermaline boards, I don’t see any advantage in additional insulation behind, just use the thickness of boards to give the desired insulation value; let it breath behind there is probably the best idea. On reading the spec sheet, it actually states not to let cables come in contact with the insulation so that answers your previous question. Downside of using Duplex boards & insulating behind is no natural ventilation behind & burying cables in insulation is not a good idea as it theoretically reduces their current carrying capacity.

 

[regsmyth]

Did you see my reply to your duplicate post you put in Decorating and Painting you naughty boy?