Best way to attach wooden sill to timber frame house build

[skeg0]

Hi!

 

Would appreciate some quick advice with regards to attaching some wooden sills to our recently constructed timber frame house.

 

You’ll see in the attached image that the timber frame is there under the plasterboard and the silver insulation. 
 

I have pine ‘planks’ to go on top of this that form the window sill but I’m not sure the best way of attaching them to the frame below. 
 

Can I for example screw/nail them through the silver insulation to the frame underneath? Or should I keep the insulation completely intact?

 

If it helps the house construction is timber frame with block work. 
 

Thanks so much in advance!

[ProDave]

Am I seeing a gap down into a cavity between the window and the silver foil?  If so that wants addressing first.

 

I just cut a strip from the plasterboard each side so the sill slides in and fill around it afterwards and mine were just stuck down.

[skeg0]

2 minutes ago, ProDave said:

Am I seeing a gap down into a cavity between the window and the silver foil?  If so that wants addressing first.

 

I just cut a strip from the plasterboard each side so the sill slides in and fill around it afterwards and mine were just stuck down.

Thanks for your reply - no gap into the cavity, just (im assuming) some black DPC. 
 

So you would put some plasterboard flat on top, screw it down and then stick down with glue/adhesive? 

[ProDave]

I didn't even screw mine down, just glued it.  It depends if you think the wood will warp or not?

 

 

See what I mean about the sill going into a slot each side cut into the plasterboard.

[Roundtuit]

Is that insulation you can see, or just silver breather membrane lapped over the timber frame?  If the window is sitting in the block outer skin, there will be a cavity somewhere.  As @ProDave says, maybe have a poke about just to make sure you don't have a cold spot.

[skeg0]

I reckon it’s just the silver breather as you say. From what I can see there is no cavity. There were gaps left and right between the vertical plasterboard at the sides of the window and the sill which I filled up with foam which you can see in the photo as there were draughts coming through there but everything else was fine. 
I read a note from our timber frame company that asks is what type of paslode nail we want to fix the sills. So I guess they suggest we nail them?!

[Iceverge]

Let the timber sills inside the house for 3-4 days to acclimate to the house first. 

 

Then glue or pin nail the sills in place. 

[skeg0]

4 minutes ago, Iceverge said:

Let the timber sills inside the house for 3-4 days to acclimate to the house first. 

 

Then glue or pin nail the sills in place. 

they have been inside for a year pretty much. But show signs of warping

 

[Iceverge]

Thats timber for you. It does that.

 

A good joiner will be able to plane it or somehow otherwise magically straighten it for you. 

 

 

 

[markc]

1 hour ago, skeg0 said:

they have been inside for a year pretty much. But show signs of warping

 

That board was destined to cup, if you look at the growth rings you can see it’s pretty much the bullseye in centre of the tree and will absorb moisture and expand much more than the outer rings.

[G and J]

@skeg0 Are you going to paint them or leave them for varnish/wax/whatever?

 

[skeg0]

10 hours ago, G and J said:

@skeg0 Are you going to paint them or leave them for varnish/wax/whatever?

 

Probably varnish I think. Seemingly can’t risk any water getting on them!

[G and J]

1 hour ago, skeg0 said:

Probably varnish I think. Seemingly can’t risk any water getting on them!

New (and better) bits of wood and glue it is then.

[Nickfromwales]

If using those, not a hardwood, then defo seal the underside / sides as well, if not better, than you seal the faces. If not these will absorb moisture from the cavities.

 

+1 for better bits of wood (sorry!). 

[Nickfromwales]

For eg 

 

Link

 

 

We then bought 30mm oak stock and faced the 18mm stuff so that when installed it looked like 30mm thick oak sills were installed. 

[ProDave]

In case I did not mention all our window boards were leftovers from the engineered Oak flooring with a hardwood bead to finish the front.  All still completely flat.