Plaster before UFH, or other way around ?

E

ennisjim

Registered User
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Hi,
I am doing selfbuild on 210sq.m bungalow and will have UFH all over. Currently roof is on and windows are in and first fix is going on. Most advice I have been getting is to gear everything towards getting inside plastering done next followed by UFH (insulation, UF piping, screed), but this is putting a lot of pressure on getting everything ready (door frames, window boards, final locations for electricals, etc). I am trying to get heating system right and don't want to rush any decisions just because plasterer is supposed to be next:)
Anyway, I got some other advice recently which I like the sound of and I just wanted to check if anyone had any thoughts or recommendations. The advice was to do first fix plumbing and then proceed to first fix UFH (insulation, pipes, screed) and do internal plastering later when I'm sure we have finalised electrics, plumbing, etc. This makes a lot of sense to me. Surely plastering is a 'finishing touch' and not something that should be done too early ?
Am I missing something ? Even my engineer is surprised I am doing UFH stuff before plasterer. The only thing he could think of is that plasterers leave a mess and I need to clean the finished floor after scratch coat and skim coats. Surely this can't be sufficient reason to rush into plastering.

Thanks
 
You have come up with a tricky one. Plastering before the screed goes in makes sense and then do the final skim plaster after the ufh and screed goes in. Plastering first will give a better seal to the floors Remember to have all your chasing done before any plastering is done. Dont put any frames etc in before you plaster, get liners put in.

And finally dont believe anything you are told as you will get different answers depending on who you speak to.

Hopefully a plasterer will post on here

noah
 
I don't think it really makes a big difference which way you do it other than what you have already mentioned about cleaning up the mess plastering can leave. If you clean up before it dries out then it should be easier to remove. You could plaster without putting in the window boards or door frame if you weren't ready for them. This is what I done and just put them up when hanging the doors. I had all oak inside so I didn't want to get them destroyed in plaster. They came out fine anyway. You could also put in skins which are cheap door frames you use during plastering and then remove them and put up the real one's when your ready. As you have said the real problem is if all the electrical stuff is where you want them to be. just make sure you have sockets every where. You can never have enough!! When all is done you will say to yourself why didn't I put one there. Also if you have your UFH done before the plastering don't turn it on until the plaster is well dried out. If it dries too quickly it will crack big time. Best of luck with the rest of the build.
 
Thanks for the helpful advice. I've done some more investigation and I'm still inclined to go with UFH+screed first and delay plasterwork until as late as possible, and I won't be turning on the UFH for quite a while after that.

Re. 'Plastering first will give a better seal to the floors'... my understanding is that with UFH there will be insulation (eg. 1inch) around the perimiter to ensure that screed does not create a thermal bridge with walls. I'm assuming here that it's OK to put insulation against bare blockwork and have plaster just come down to meet the top of the insulation. I guess this will be hidden behind skirting boards anyway.
 
plaster first.

One reason is that plasterers work down as low as they can with the skim, and the screed then comes up above the line at the bottom, and you get a good clean line.

This isn't possible when the floor is in first - it's very difficult to plaster down to a definate edge cleanly - stopping the trowel at the floor makes it hard to finish. Also, when they 'wipe' upwards with the trowel, and the floor is in, it's inclined to bring dust/debris from the floor up into the plaster finish.

Plaster first, my 0.02
 
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