Wet plaster or dot and dab for my self build?

[Berkshire_selfbuild]

Hi all. We’re at first fix stage of our self build (cheeky pic added) and need to make a decision of going traditional wet plaster or dot and dab plasterboard. My build is thermalite blocks inside, 100mm pir plus 50mm air gap, and then my facing bricks. I have MVHR going in and hoping for reasonably high levels of airtightness as possible. I have only ever lived in properties with traditional wet plaster and am used to solid feeling walls and being able to hang up TVs etc without issues, and generally the feeling of solidness and quality which I’m worried dot and dab won’t give me. Any wise words of wisdom out there to sway me one way or another? It’s a home for life so want to make sure I make the right decision.

[nod]

I run a plastering and render company and have chosen dot and dab on both our builds A much warmer feel 

If there’s enough dabs and the correct fitting You can hang anything 

Airtightness is about the same Someone will be along suggesting Parge Don’t bother Only self builders use this Better to make sure your block work is pointed and sealed around the joists properly 

[Ben1984]

Nod would know much more than me, but given you have thermalite blocks on the inner skin I would imagine wet plaster could be problematic/prone to cracking. I want a wet plaster finish on our build and I have specifically avoided using a thermalite block to accomodate this.

Edit: Using wet plaster would also slightly reduce the u-value of your wall (when comapred to dot and dab) - has this been factored into to the overall u-value of the wall?

Edited June 26 by Ben1984

[Gone West]

8 hours ago, Berkshire_selfbuild said:

I have only ever lived in properties with traditional wet plaster and am used to solid feeling walls

I have lived in a large number of different houses and I agree that a traditional wet plaster finish feels best. If you can find a good plasterer who can do a good job with a bonding coat and a finishing coat then go for it. Finding a decent old school plasterer who can do it though might be difficult. 

[FarmerN]

27 minutes ago, Gone West said:

 Finding a decent old school plasterer who can do it though might be difficult. 

+1

Harder to get the window reveals right with wet paster. We did wet plaster and I am happy with it,it was on top of dence blocks not thermalite. The plasterer was incredibly slow and some of the reveals were hard to get right as too thick a layer of plaster was required.

Edited June 26 by FarmerN

[nod]

Just to add If you do decide to wet plaster Sand and cement is a better option than most of the bagged stuff 

The only bagged stuff that we use now are the renovation plasters Limelight etc Very expensive 

20 years ago Wet plaster and dd was Bout 50% of our jobs Now Not counting render Its about 10% of our plastering work 

Cost wise sand and cement works out about the same as dot and dab More for labour Less for materials 

[Berkshire_selfbuild]

Thanks all for the super useful info. I’ll find out if my main contractor has a plasterer who is reliable to do wet plaster. Otherwise will go down dot and dab route but make sure it’s done properly and sealed around the edges etc.

[crispy_wafer]

🤣  I Parged, then I d&d because i didnt have anything better to do with my time.  As above, ensure enough adhesive in the correct places.  Work out your main hanging points so extra adhesive can be added here.

[Berkshire_selfbuild]

9 minutes ago, crispy_wafer said:

🤣  I Parged, then I d&d because i didnt have anything better to do with my time.  As above, ensure enough adhesive in the correct places.  Work out your main hanging points so extra adhesive can be added here.

What is all this ‘parge’ I hear of? 

[crispy_wafer]

Just sealing up of the blockwork, filling up the visible pores and sealing over the mortar joints of the inner face of blockwork with either a product called sound coat, or a sand and cement mix.  Not needed if you go float and set (wet plaster).  But if dot and dab its a secondary measure to cover your backside if the brickies haven’t been quite as diligent as they should have been.  A couple of days labour for me and the mrs, but if paying someone I may have thought twice about it, doesn’t need to be neat!

[Nickfromwales]

3 hours ago, FarmerN said:

The plasterer was incredibly slow and some of the reveals were hard to get right as too thick a layer of plaster was required.

Plaster is a finisher not a filler, so the prep work wasn’t done properly here. The boards make up the reveals, or you batten and bond out, and the beads get set straight/plumb and that’s a done deal. 
 

I’m a decent plasterer but too slow (OCD) to make money from it, but I’ll put a stop bead against the window and a regular bead at the reveal, and run the trowel across the two for the first couple of ‘rubs’ and then polish up from there.

 

Laying on plaster thick is a complete pain in the ass, as it’s like moving jelly around a plate. 

[Kelvin]

3 hours ago, Berkshire_selfbuild said:

Thanks all for the super useful info. I’ll find out if my main contractor has a plasterer who is reliable to do wet plaster. Otherwise will go down dot and dab route but make sure it’s done properly and sealed around the edges etc.

The other thing to factor in is the extra time plastering adds in and it makes a right mess. You can put down sheets and protect all the windows, woodwork, doors or whatever else is in place. 
 

We debated going taping and filling vs plastering (timber kit) and went plastering as I preferred the finish but we would have been much quicker taping I think. We also had to sack the first plasterer as he was crap and that added another several days as I had correct all his shoddy work. 

[Nickfromwales]

1 hour ago, Kelvin said:

The other thing to factor in is the extra time plastering adds in and it makes a right mess. You can put down sheets and protect all the windows, woodwork, doors or whatever else is in place. 
 

We debated going taping and filling vs plastering (timber kit) and went plastering as I preferred the finish but we would have been much quicker taping I think. We also had to sack the first plasterer as he was crap and that added another several days as I had correct all his shoddy work. 

You’d have regretted tape and joint for the rest of your days. 
 

Just utter crap and when there’s light on the walls you see every single joint. 
 

Plaster every day of the week, unless it’s a school room or an office. 

[JohnMo]

1 hour ago, Nickfromwales said:

You’d have regretted tape and joint for the rest of your days. 
 

Just utter crap and when there’s light on the walls you see every single joint. 
 

Plaster every day of the week, unless it’s a school room or an office. 

Really - tell that to nearly every house in Scotland built over the last 40 years. We are taped joints, no issues. Finish is good as the person that does it. Unlike England plasterboarding is a joiners scope in Scotland, so none of you dob and dab malarkey. Tapers are another trade and that is pretty much all they do.

 

Some of our walls are 6m tall, the majority oven 2.4m so plenty of joints. We had a good guy doing ours. He was really specific to what materials needed to ordered and would not accept anything else.

[Kelvin]

It definitely varies. I’ve been in houses that were taped and they looked perfectly fine even with light falling on the walls at the right angle. The plastering in our previous house was clearly done by different people as some of it was flawless and some of it was terrible. 

[Gone West]

The third house I owned was dot and dab and taped and it looked fine.

[Nickfromwales]

1 hour ago, JohnMo said:

Really - tell that to nearly every house in Scotland built over the last 40 years. We are taped joints, no issues. Finish is good as the person that does it. Unlike England plasterboarding is a joiners scope in Scotland, so none of you dob and dab malarkey. Tapers are another trade and that is pretty much all they do.

 

Some of our walls are 6m tall, the majority oven 2.4m so plenty of joints. We had a good guy doing ours. He was really specific to what materials needed to ordered and would not accept anything else.

Take a completely flat sheet of plasterboard, and then lay the mud on the joint, then apply the tape, then add more mud, and then sand back. That is the process/build-up.

 

Outcome, a high point on each junction; tapered vertical joints can be smoothed well, but tapered board ends are square and the taping and filling process there makes for even higher/prouder joints. They then have to be blended into the vertical.........

 

The only way to reduce that is to feather the filler across a much bigger surface area and blend it out, I know because I have done so myself previously; I therefore have 'hands on' experience vs just an opinion! Upshot was, the huge amount of time, effort, dust, mess (cost) vs a wet skim makes this zero sense whatsoever.

 

Kudos to good guys who have done a good job, but you can't argue that there are no bumps created by the taping and filling, because there are, and you can see these without looking too hard, from my direct experience.

[Oz07]

Another consideration. Aren't walls a lot more durable with skim on too? Like you try denting a normal sheet of plasterboard with your knuckles or a hammer versus denting a board that's been skimmed. For some reason its alot harder than you would imagine 3mm of skim makes it. Don't ask me why, science!

 

 

[JohnMo]

2 hours ago, Nickfromwales said:

Take a completely flat sheet of plasterboard, and then lay the mud on the joint, then apply the tape,

The whole point is you definitely don't start with a flat sheet you use taper edge sheet. The tape etc sit in the taper.

 

17 minutes ago, Oz07 said:

Aren't walls a lot more durable with skim on too? Like you try denting a normal sheet of plasterboard with your knuckles or a hammer

Maybe true if you go around your house hitting the walls - maybe some anger management is needed? 😁 Never seen an issue myself.

[Oz07]

Durability is a concern if you have kids, or anger issues, or even worse kids whose behaviour gives you anger issues!

[Nickfromwales]

20 minutes ago, JohnMo said:

The whole point is you definitely don't start with a flat sheet you use taper edge sheet. The tape etc sit in the taper.

That's exactly what I just wrote?

 

2 hours ago, Nickfromwales said:

Take a completely flat sheet of plasterboard, and then lay the mud on the joint,

🙃

[Mattg4321]

Tapered edge board is fine until you have to join the short edges (which are not tapered) on a ceiling etc