Painting hidden plaster - Should I bother?

I'm painting an new kitchen extension (and garage conversion) with screwfix's new plaster paint (doesn't need thinning) but I'm just wondering if there is any advantage in painting hidden plaster? We're having a kitchen installed so lots of the kitchen will be hidden. Is there any point in painting these areas or am I just wasting time/money I don't really have (I've got lots to paint including a bedroom and large garage conversion!)? Anyone any experience in this?

Also any experience in drying new plaster - some of it has been 8+ weeks and still wet (even more so around the metal edging strips in the plaster). Wet cold weather isn't helping so i'm tempted to try a heater and/or dehumidifer... There is good airflow as the garage door still hasn't been replaced but it's not really helping.

Personally I wouldn't bother painting it if it's never going to be seen, I'd imagine your kitchen is going to be pretty permanent, so only you will know.

I've been recommended against using dehumidifiers to dry plaster as it can crack it. I had my kitchen replastered last year and it dried in a couple of days - maybe a different mix/type?

Quote:

---

Originally Posted by cheesemp

I'm painting an new kitchen extension (and garage conversion) with screwfix's new plaster paint (doesn't need thinning) but I'm just wondering if there is any advantage in painting hidden plaster? We're having a kitchen installed so lots of the kitchen will be hidden. Is there any point in painting these areas or am I just wasting time/money I don't really have (I've got lots to paint including a bedroom and large garage conversion!)? Anyone any experience in this?

---

Bare plaster isn't particularly dampproof/waterproof; any moisture that gets on it will soak straight in. In a kitchen it's going to get damp, so I'd put at least one coat on it just to protect the bare plaster. It might not be an issue, but damp can encourage mold and mildew, so I'd say it's worth doing.

Quote:

---

Originally Posted by cheesemp

Also any experience in drying new plaster - some of it has been 8+ weeks and still wet (even more so around the metal edging strips in the plaster). Wet cold weather isn't helping so i'm tempted to try a heater and/or dehumidifer... There is good airflow as the garage door still hasn't been replaced but it's not really helping.

---

Had all sorts of bits of our house replastered recently and it's never taken more than a few days for it to dry out. If oyu have new plaster that's still wet 8 weeks later there's something wrong with it: I'd get in touch with your plasterer to see what's going on...

My bedroom is on outside wall with no adjacent building. So I had an issue with mould on the top corner of the room, so we stripped the wallpaper and the lining paper. Treated the entire walls to anti-fungal treatment, naturally dried it. Then had the room plastered and was advised AGAINST using a dehumidifier. Always best to let plaster dry naturally for best results.

Can't remember for the life of me though how long we left it before we painted the bedroom as opposed to putting wallpaper up.

So I ended up putting a coat of some anti-fungal paint/treatment then went over it with Matt White paint. Literally got no mould growing except where it grows naturally on or around the windows. So I just go over it with a cloth and anti-fungal spray and keeps it at bay, essentially under control.

We had plastering done in Spring last year and so far, no cracks or places that I need replastered.

(Apologies for going OT slightly lol)

Quote:

---

Originally Posted by scaryjim

Had all sorts of bits of our house replastered recently and it's never taken more than a few days for it to dry out. If oyu have new plaster that's still wet 8 weeks later there's something wrong with it: I'd get in touch with your plasterer to see what's going on...

---

Problem is there is a) Lots of it (large kitchen, utility room, toliet and family room), b) Its mostly rendered walls rather than plasterboard (the plasterboard skims dried almost within a day) so quite thick, c) No heating in this area of house due to a screw up with radiator supplier while my plumber was on site - It's warmer than outside (not freezing) but still pretty cold due to drafty garage door. Main issue seems to be around the beam we had installed and metal plaster edging strips. I think the metal is getting too cold and attracting moisture. I think I might have to get a heater going...

Thanks for the advice guys - I think I'll give most of it one coat then.

I'd say no, but if it's been a week and your plaster is still wet then it sounds like ventilation is poor in your kitchen. As pointed out above, if the plaster isn't sealed then it's going to absorb moisture quicker. So in your situation, I'd be inclined to seal it.

Drying out plaster too quickly can cause cracks, but you've had it sat around for a week already, so it sounds like it could do with a helping hand.

Quote:

---

Originally Posted by Dashers

I'd say no, but if it's been a week and your plaster is still wet then it sounds like ventilation is poor in your kitchen. As pointed out above, if the plaster isn't sealed then it's going to absorb moisture quicker. So in your situation, I'd be inclined to seal it.

Drying out plaster too quickly can cause cracks, but you've had it sat around for a week already, so it sounds like it could do with a helping hand.

---

I've had a two windows open at the locking ventilation position and its got air coming in through the drafty garage door (its through an open door way but still ventilation). Only exception to this has been when its dropped below freezing when I've shut the windows but its still had some air coming in. To be honest 95% is drying ok its just the bits around the metal work that isn't. I might have try heat then move onto a dehumidifier if that fails as we ideally need it painted before installation of the new flooring...

If the metal is exposed it might be attracting condensation and then the plaster may be drawing it up. you might be better off hiring one of those garage type heaters for a week or so to get the temps up.

Quote:

---

Originally Posted by MaddAussie

If the metal is exposed it might be attracting condensation and then the plaster may be drawing it up. you might be better off hiring one of those garage type heaters for a week or so to get the temps up.

---

Yes that might be it. The plaster edging strips are mainly embedded in the plaster but the edge is just visible in places... I'll get my convection heater going and see if that helps...

Edit: Its something like this http://www.diy.com/departments/galva...m/35775_BQ.prd
Edit 2: I wonder if some of the fresher plaster drying in the garage is making the atmosphere quite humid... I'll stick a dehumidifier in the kitchen (the oldest part of the plastering) and leave it on low with the heater I think.

Quote:

---

Originally Posted by cheesemp

Edit 2: I wonder if some of the fresher plaster drying in the garage is making the atmosphere quite humid... I'll stick a dehumidifier in the kitchen (the oldest part of the plastering) and leave it on low with the heater I think.

---

did it pull much moisture out?

Just consider how much water a plasterer mixes with the gypsum - and then spreads over the wall, and then think that the majority of that is going to evaporate through the body of the plaster...

As for painting the hidden bits - from a practical point it would seal the surface. From a personal pop, would you be happy knowing that you had not done it? :)

as people have already said, unpainted plaster will absorb moisture, and give off that unmistakable smell of "wet plaster". For mould resistance, air quality and your own sanity paint it. Properly, and for a kitchen use a moisture resistant wipe-down paint. Ideally mould resistant (particularly to concealed, hard to get to areas). Mould WILL grow quite happily behind cupboards etc. You just don't want that.

Quote:

---

Originally Posted by cheesemp

Main issue seems to be around the beam we had installed and metal plaster edging strips. I think the metal is getting too cold and attracting moisture.

---

Is it unheated garage space or internal habitable space? If the latter and it is recently installed then it does not sound like this complies with building regs. It does not take too much insulation to lag the steel to suitable standard. Building regs also wants steels in houses (including in attached garages) to be fire protected - does it have intumescent paint or fireboarding? You need one of these two (if it's supporting rooms above - which it presumably is if they went to the trouble of putting in a steel.) You could kill two birds with one stone by lagging the beam with insulation and boxing-out with fireboard to give a neat face for plastering round (if you want to finish the garage). Internal beams inside the house should NOT be capable of getting cold enough to cause a damp problem if installed to modern regs.

Quote:

---

Originally Posted by ik9000

Is it unheated garage space or internal habitable space? If the latter and it is recently installed then it does not sound like this complies with building regs. It does not take too much insulation to lag the steel to suitable standard. Building regs also wants steels in houses (including in attached garages) to be fire protected - does it have intumescent paint or fireboarding? You need one of these two (if it's supporting rooms above - which it presumably is if they went to the trouble of putting in a steel.) You could kill two birds with one stone by lagging the beam with insulation and boxing-out with fireboard to give a neat face for plastering round (if you want to finish the garage). Internal beams inside the house should NOT be capable of getting cold enough to cause a damp problem if installed to modern regs.

---

Sorry I didn't see this post. The issue was cold winter air getting to the metal plaster edging strip not the steel beam under it I think - due to the very edge of being bare in the corner it just drew in the moisture to the plaster. In the end I painted it with the breathable plaster paint I had and it appears to have dried out along with the help of the radiator being connected and the old garage finally being sealed up. It has left a bit of a water mark on the paint though. Hoping this will disappear when I paint the 'beam' with our wipeable 'kitchen' paint although I'm leaving it as long as possible to dry out before doing that. The odd part of all this is everything else dried pretty quick...

Quote:

---

Originally Posted by peterb

Just consider how much water a plasterer mixes with the gypsum - and then spreads over the wall, and then think that the majority of that is going to evaporate through the body of the plaster...

As for painting the hidden bits - from a practical point it would seal the surface. From a personal pop, would you be happy knowing that you had not done it? :)

---

I did do it all in the basic plaster paint. I only did the visible bits with the kitchen paint...

I know I'm late (too late) to the party, but I too would hive it at least a sealing coat.

As for bring lots of it, in a building environment where masking needs would be minimal, a spraygun would be (well, was) my choice. You can cover a hell of a lot, quickly, even if you do two or three light coats.

Thanks Saracen, too late I'm afraid. Did it all by roller. Spraying might have been a good idea too (before the flooring went in) as the roller left it a little lumpy in places when I was doing it before the lighting went in... Oh well live and learn (not to have building work done :help:).