# Window Sills? (internal)



## Chems (29 Oct 2010)

Fitting a window sill?

I've got the odd job this weekend to fit an oak windows sill. What's the lay of the land on this, its oak and wants to be hole less really, but don't want to glue it down if you guys think it wont hold. A proper job needs to take place, as its for my dad! The last one bowed up an broke away from the plaster beneath, but that was the window fitters fault/builder as no expansion room was left. 

TIA


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## cgw59 (29 Oct 2010)

Hi , I assume it's an indoor sill board that you have to fit , if it is a method that I have used successfully in the past is to screw heavy gauge 35 - 40mm brass screws to the underside of the board , then drill holes into the masonry surface that it will sit on and fill them with either a thin mix of rapid set cement or epoxy putty, then push the screws fitted on the underside of the board down into the mix nd set some weights on it until it has hardened. Some beads of adhesive on the underside will add grip to the whole area and this method will leave not signs of how the board has been fitted. hope you get the idea and find it a help.


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## devonwoody (29 Oct 2010)

When mine where fitted 20 years ago long screws and plugs were placed in the top screw holes. Timber was left bare with just a sanding sealer and have never moved. Must depend on the timber quality I suppose.


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## AndyT (29 Oct 2010)

Maybe worth mentioning that good practice is to run a tongue along the edge of the window board to fit into a groove ploughed across the bottom horizontal part of the window frame. So it's worth extracting the old one first, and if it has a tongue on it, copy that on the replacement.


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## jasonB (29 Oct 2010)

Get some bat straps with a bend in them, screw to underside of window board and chase out plaster so they can be screwed to the masonary and then filled. The straps will hold them down and also stop any tendancy for the board to cup.

You can also put a load of screws into the underside and set the board on an inch or so of drywall adhesive.

Jason


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## johnf (29 Oct 2010)

jasonB":wcfp5yu3 said:


> Get some bat straps with a bend in them, screw to underside of window board and chase out plaster so they can be screwed to the masonary and then filled. The straps will hold them down and also stop any tendancy for the board to cup.
> 
> You can also put a load of screws into the underside and set the board on an inch or so of drywall adhesive.
> 
> Jason



Thats how hundreds of thousands of window boards have been fixed on building sites everwhere


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## chippy1970 (29 Oct 2010)

Window boards on the inside NOT sills :roll: 

Anyway we normally fix MDF ones with expanding foam but for your oak ones i would be tempted to strap them down as said above.


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## Chems (30 Oct 2010)

Thanks,

The window is PVC. 

Tempted to go the easy use with some DryWall adhesive. 

Not 100% sure on what the bat strap method is.

Do you mean mount the straps along the short length, as in coming off the window at a tangent, not inline across the window?


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## jasonB (30 Oct 2010)

They are an L shaped bar that has holes all along its length like this

The short leg of the L is screwed to the underside of the window board, the long leg extends down the wall 2ft or so and is screwed to teh masonary and subsequently plastered over or you can chase out the plaster, fix and then fill the channel.


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## chippy1970 (30 Oct 2010)

Chems":2mlt30so said:


> Thanks,
> 
> The window is PVC.
> 
> ...



I wouldnt use Drywall adhesive its very wet you want to avoid moisture near a timber board un less you are sealing them fully before you are fitting them. You would bet better off using expanding foam or try the newer dot and dab foam if you dont strap them down make sure you weight them down or the foam wil lift the boards.


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## liam8223 (30 Oct 2010)

Only my recent experience, but i have dropped my solid oak window boards (made by me) directly into the aperture and they haven't moved a bit. been there nearly 8 months so had plenty of temp and humidity changes.
Took it back out today to fix it down, just going to evo grip it to the plasterboard, in the same vein as using grip to fix skirting, should be more than strong enough.

Am i Wrong?


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## Chems (1 Nov 2010)

Well Karl was over early on saturday morning so asked his advice and had a look at it. He said to seal it fully an stick it down. So we did.

Finished article:




If I'd chosen the piece I'd have probably not got a character piece and instead got a prime piece with no knots, buts its all characters. Used a 2 part epoxy to stabilise and fill them.


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## liam8223 (1 Nov 2010)

looks spot on to me, mine ar alot thicker tho, 32mm.
got a bit over keen when ordering the AW oak!


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## Chems (1 Nov 2010)

Well these were about 20mm I think, had to match the size of the ones that came out. 

Forgot to say, used No Nails to stick it down, after sealing both sides with a few coats of danish oil.


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## chippy1970 (1 Nov 2010)

Chems":2ow1gl9v said:


> Well these were about 20mm I think, had to match the size of the ones that came out.
> 
> Forgot to say, used No Nails to stick it down, after sealing both sides with a few coats of danish oil.



hope that wasnt solvent free no nails its rubbish we have stopped using the yellow solvent free gripfil now on new builds a lot of the skirtings etc have popped off the glue doesnt bond very well with the plaster walls. The newer mastic type glues "sticks like s**t" and that type are great if a little expensive.


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## Karl (1 Nov 2010)

Nice job James. I meant to send you a pic of the ones i've done at home, but I forgot. 

I've had that too Chris - the cheaper non-solvent based grab adhesives seem to dry quite chalky and really don't grab very well (if at all). Solvent based all the way for me.

Cheers

Karl


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## bench_monkey (1 Nov 2010)

given half a chance everything i do would be stuck with original grey gripfill :lol:


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## Shane (1 Nov 2010)

bench_monkey":2njmy4tp said:


> given half a chance everything i do would be stuck with original grey gripfill :lol:



I find that it skins over too quickly, I prefer ceresit PL600 which is a similar colour


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## bench_monkey (1 Nov 2010)

Yeah i know what you mean Shane, problem is that experience has taught me to only apply gripfil once you are 110% CERTAIN it will fit. it wasnt easy to remove, trust me :lol:


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## jasonB (1 Nov 2010)

Unlike the green gripfil Evostic do not suggest plaster as a suitable surface for the yellow solvent free one, perhaps thats where you have been going wrong Chris & Karl

Solvent
_"A high strength, one part, gap filling adhesive
specially formulated to bond a large variety of
materials such as: plywood, blockboard, chipboard,
hardboard, laminated plastics, rigid uPVC (excluding
foamed PVC), rigid insulation materials (excluding
expanded polystyrene), metal sheeting (including
aluminium, steel, galvanised iron, tin plate and
nonferrous metals) to themselves or to brick, stone,
breeze block, sand/ cement screeds, concrete,
*plaster*, plasterboard and insulation boards."_

Solvent Free
"_Wood, plasterboard, MDF, hardboard, ceramics,
glass, metal, cork, laminates, uPVC, brick, breeze
block, concrete, most plastics etc. At least one
surface should be porous"._

I think the problem is plaster is too absorbant and sucks the moisture out of the adhesive before it can properly cure, and who has time to seal plaster before using gripfil?

Jason


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## Chems (1 Nov 2010)

TBH honest could have gotten away with out gluing it at all. It was a very snug fit once we'd glued some packers down at the back of the board closest to the window and the metal corner strips on the block work of the brick dug into the wood at the front so it was more trapped in place than glued. 

Not sure what type of No Nails it was, the tube was black and new. Screwed the new skirting on an filled the holes so no need to worry there.


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## chippy1970 (2 Nov 2010)

jasonB":bzntvqwv said:


> Unlike the green gripfil Evostic do not suggest plaster as a suitable surface for the yellow solvent free one, perhaps thats where you have been going wrong Chris & Karl
> 
> 
> 
> Jason



Exactly as you say the fresh plaster sucks the moisture out of the glue before it can bond, it wasnt down to me it was just the stuff that the main contractor supplied I stopped using the water based stuff years ago.

I agree with Shane with the green gripfil it does skin over too quick.


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