SillyBilly

Thanks for replies so far. Didn't see them as no email notifcations received. Still thinking about it

Hi, I take your point but both examples were on architect designed houses and had BC approval. In my case the 2.7m window will be in a single storey lean to part of the extension so deflection isn't a concern to me. With my builders merchant only stocking eased regularised KD timber I need to know what to search other suppliers for. What standard size timber headings would have been used in the gapless case in my first pic? I have already faced inflationary rises in my project which is why I am trying to order the timber

I am studying an actual construction of 4 houses. Pics from 2 of these show the 225mm 3-ply timber lintels over 2.7m openings

I am ordering materials for a self-build annexe. The studwork is eased 47x150 which I am told is reduced in each dimension. I am puzzled as to what to use for the timber lintols. I was planning to use 3-plys of the same as the studwork bearing on 1 stud for 1200mm openings, on 2 studs 1800mm, and 225mm bearing on 3-studs for an opening of 2700mm. I have attached 2 pics showing my concern. My Builders Merchant has standardised on eased timber which leaves a gap as in a picture taken from the construction of another house. The alternative is to find a stockist of non-eased kiln dried lumber which would give a 3-ply lintol as in second picture. What do people recommend. Is the gap allowed?

I am building an extension. Have done the beam and block floor. Plan to have 150mm celotex or similar standing on a 1200 gauge polythene dpm joined to downturned 450mm dpc. I am not installing UFH and am considering a floating floor of glued 22mm t&g panels standing on the PIR or possibly engineered wood flooring. Is that suitable and do I need another dpm over PIR as not pouring screed on it?