# fitting front door frame - correct way to seal cill



## fobos8 (20 Feb 2013)

Hi guys 

I've got a front door frame to fit for my dad and I just want to check on the correct detailing where the frame threshold meets the sub cill.

The frame has a flush cill, i.e it doesn't protude past the frame itself and there is no drip groove. The granite sub cill is at dpc level. The first 30mm of the granite cill is flat and past that it slopes down nicely.

My initial thoughts are fit the frame so the front of the timber cill is flush with the front of the flat part of the granite, sit it on some packers and the seal between the frame and granite cill. 

like this






Is this the correct way to do it?

I've seen people fitting a piece of dpc that is nailed to the inside of the frame and then extends under the frame to the outside. Is this really needed for this?

Best regards, Andrew


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## carlb40 (20 Feb 2013)

The dpc was nailed just to stop it flapping about during door/window installation. I would probably still use it just to be on the safe side - re damp. Make sure when you pack the cill up, that you pack the centre aswell. Not just under the frame legs.

Unless the floor/ granite cill is bang on level, you may have to pack one side anyway. So you may aswell lift the whole thing clear of damp issues. 

Oh and i would put some form of preservative on the bottom of the cill before installing.


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## fobos8 (21 Feb 2013)

carlb40":24wbyo7p said:


> Oh and i would put some form of preservative on the bottom of the cill before installing.



paint or something else like liquid bitumen?

Is the dpc to stop the door cill getting damp or dampness getting in the house?

cheers, andrew


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## Graham Orm (21 Feb 2013)

The priority is to stop the cill getting damp from the outside course. There's nothing above it so it can't really transfer damp up and in. As long as you put a piece of DPM under the front edge or sit it on a bed of sealant the drawing you have shown looks fine. Then a bead of sealant along the outside to stop penetrating weather and give a neat finish. If it's softwood I would give the bottom a coat of something too to be on the safe side.

Use sealant to fix the packers in place or they may move over time. The threshold will inevitably get stood on and knocked, the door will get slammed and the wood may shrink, all of which may allow them to become loose and move.


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## carlb40 (21 Feb 2013)

fobos8":34aegswp said:


> carlb40":34aegswp said:
> 
> 
> > Oh and i would put some form of preservative on the bottom of the cill before installing.
> ...



Whatever you have lying around will be fine. If you paint it, make sure it gets glossed aswell. Undercoat will still allow moisture in. 
A few coats of varnish will do the trick. It will have no weathering on it, just needs to be sealed in case the sealants etc ever fail.

The dpc is to stop damp rising up into it. 
The cavity is designed to allow for insulation, air flow and stop any moisture from the outside transferring into the interior.


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## fobos8 (21 Feb 2013)

could I point the gap between the granite and the timber cill with mortar (which would look better with the granite) or is sealant better??


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## carlb40 (21 Feb 2013)

You can do, just be aware of movement from the timber etc plus maintenance . Another option and what i do if the floor is bang on level - bed the frame on silicone first and seal again after. That way when the outer sealant fails, the inner one should stop any water.

So you could put a bead of sealant down, say 15mm in. Then point the frame after


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## Graham Orm (21 Feb 2013)

fobos8":27o3f7sh said:


> could I point the gap between the granite and the timber cill with mortar (which would look better with the granite) or is sealant better??


 I guarantee it will crack and fall out, far better using a flexible sealant.


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## fobos8 (21 Feb 2013)

thats it then sorted - many thanks to you all


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