Compliant Window Installation Design Detail - Barn Conversion with Solid Walls

[Beagle2]

Hello,

 

I'm starting drawings for full plans approval to install windows on my small barn conversion.

 

Walls are solid 'rubble masonry' with lime mortar (pic below). The original windows (Crittall type) were just nailed into masonry and mortared around. 

 

I can't seem to find a suitable detail for solid walls. The book I bought is all for modern construction with double skinned walls, cavity closers, air tightness tape etc.  

 

I've had wooden casement windows built and want to install the units onto large slate cills.

 

The window joiner said just put a strip of DPC beneath the cill and secure using wedges, fasteners, expanding foam etc.   

 

The wall should be able to breathe (lime mortar) so I don't see what the DPC adds. 

 

Can anyone recommend a publication/source for windows in barn conversions? Basically like the attached drawing but for solid walls

 

Thanks everyone

[jfb]

I would say that what your joiner has suggested is reasonable. It’s basically what I did on mine.

I didn’t use dpc but can’t see any harm in it.

mine sat on existing cills that fell off immediately from where they were sat. Lime mortar to finish.

i spent some time getting the inside details right for my setup as I was installing wood fibre board insulation internally. So got full layer of insulation on reveals and under the internal cill (wood on the inside) before rendering.

expanding foam can probably do the fixing job on its own (make sure you get low expansion stuff designed for windows) but straps for belt and braces.

[Beagle2]

Thanks jfb,

 

re. existing cills, do you mean angled down immediately from the base of the window? Or fell off due to a lack of suitable fixings :)?

 

Shall I mock up a drawing as the joiner describes and submit to BC? Ideally I want to reference some sort of best-practice guideline. But as mentioned can’t find anything for old barn conversions. 
 

I want to get it right first time as some of the other works have taken a bit of, er, discussion. (This has always been down to differences in heritage/modern techniques)