Can you use plasterboard for window jambs, reveals, sills?

[elbow]

hey guys - i've been here asking a few related questions and some of the helpful answers are now leading me to this question.

I had new PVC windows fitted but i refused to have any timber surrounds.

After browsing the internet, most suggestions are to use plasterboard - But now it has been pointed out that any moisture resting on the plasterboard is not healthy so i would like to ask for advice on what i should use/do?

There are also suggestions to use insulated cavity closers, but i cant see how i would fit them as the windows are attached to the outside wall (double-brick). I don't want to use wood anywhere - Can i use PVC or something moisture resistant instead of the plasterboard?

As always, your help is massively appreciated and my hurting head will be forever thankful 🙏🙏😁

[JacobZ]

Hi @elbow,

This is a bit of a challenge you've given us. The only alternative I can think of, outside of timber, is render.

Could you please clarify your hesitation towards using timber? In this context, timber seems like the optimal choice for finishing off the windows. It provides a robust surface that, when properly painted, offers superior weather resistance compared to plasterboard.

I'm eager to hear the reasoning behind your reluctance to use timber. In the meantime, I'll also reach out to some of our knowledgeable members for their input: @Dave-1, @Jewelleryrescue, @Nailbag.

Jacob

[elbow]

Hey Jacob Re the wood - we live in the blue mountains and want to avoid the possibility of termites as much as possible and also maintenance - The previous architraves were a sight to behold and a lot of timber, some of which had shown signs previously of termites and rotting.   

[EricL]

Hello @elbow 

Thank you very much for the explanation on your reluctance to use timber. Would it not be possible to safeguard against termites say a chemical barrier placed in front and around the window? Aside from the suggestion of rendering, have you considered putting something like DECO Western Red Cedar Deco Clad End Cover Channel.

It might be possible to assemble it into a square to act like a window frame, however, my only worry is that it might not be deep enough to cover the gap you currently have.

Let me call on our experienced members @TedBear, @diy_hausdesigns and @JoeAzza for their recommendations.

If you have any other questions we can help with, please let us know.  

Eric

[elbow]

Hey Eric, thanks for the shout.

I'm not a fan of the chemical barrier stuff as I've read that it can be hit n miss. I'd rather just avoid the little blighters altogether  😁

the cladding would break the bank - ive got a lotta window to fix up!  😪

Hopefully the other chaps can advise when they get a moment, massive thanks Eric 🙏

[Dave-1]

Morning @elbow 

Following on with some more ideas

How about Ekodeck 137 x 23mm 5.4m Riverbank Red Designer Edge Board Composite Decking as the window sill and plaster the vertical and the top?

I wouldnt normally suggest it as its a composite with plastic in it but termites wont go near it is my main thinking.

Will keep mulling it over

Dave

[Noyade]

That looks good Dave.

Do we have the dimensions?

[Dave-1]

Morning @Noyade 

hahahha I just realised you were asking for dimensions for the window sill and edge You know when you have too many things going on in your mind

Just to have the info at our fingertips the ekoboard is 

137mm * 23mm plus 5.4m long

Dave

[elbow]

Hey Dave

Nice idea - i'm still concerned about whether there is a possibility of damp coming thru the plaster. I have seen this in the past but only occurred to me now i have to do it myself  🤔  The other thing is i really just want a plaster - look around the whole window, so no wooden sill, at all. It seems a lot of youtubers go with plaster-board all round but my concern is still the damp - i have no experience on what happens if i do use plasterboard everywhere and should i be concerned about the damp? still confused about that 😕

[Dave-1]

Afternoon @elbow 

I am not particulary worried about vertical surfaces with moisture, just window sills/door ways ect that have the potential of water sitting on a flat surface.

Garage lining for stud walls stage 1  step 3 shows how I have put plaster up to edges on brickwork but always have timber on the bottom. I have attached plaster directly to brick to save space and its still there 3ish years later

As to the look around the window you could still do with timber/timber pieces, you could source thnner timber (12mm) and paint it the same so it looks like plaster but has a better stand up to water. Just remember youtubes showcase perfect stuff, generally they dont show what happens down the path. I get my ideas from them but ballance that out with what I think cna happen.

Dave

Dave