Sunday, 26 June 2011

On with the roof, Part 2

 Although the joiner guys I employed had fixed all the trusses they were unable to finish the trusses around the openings for the roof lights. That was left to me!!!

Here I am fixing the remaining roof members around the roof lights

Never having built a roof before I needed to take some guidance on the next steps. Most of my skills have been developed by employing the techniques learned from considerable reading and dedicated observation of the professionals as well as lots of practice over the many years that I have been doing construction jobs, both at home and for other people. This job was to be no exception and the one really useful piece of  literature that I used to construct the roof was Kingspans guide to insulated roofs. A small booklet which lists the different types of roofing construction methods involving tiles, tile battens and roof membranes. Being the person I am I chose to follow the most involved method of construction which does  produce the most thermally efficient roof but is also the most complex, that method is called in their booklet a 'sealed roof' ie:- sealed all around the edges and between the different courses of membrane so that there is no path between the outside air and the air under the membrane. Normally accepted methods involve draping the membrane between rafters and not sealing between the subsequent layers whereas my chosen route demands a taut membrane and the sealing between layers which presents some difficulties and non-standard methods of construction, of course!!
Because the membrane is taut the tile battens cannot be fixed directly to the rafters as there is no way for any water to drain so counter battens are required. (see pictures) A further difficulty was how do I  access the second and subsequent courses of membranes to remove the release film between layers.

Preparing the valleys


The Tyvec membrane used here is non regular 1.5m width with adhesive seal.
Well the solution was to cut the counter battens to just short of the width of the membrane and fix the lower tile battens first to provide a ladder to access the next layer, simple!!

Working up the roof fixing battens to form a ladder to fix the next membrane course
Working out the solution to the next problem caused some head scratching. Of course the professionals out there will work this one out in their sleep, "spacing of the battens", One roof with two sides may be fairly simple, fix the top and bottom batten, measure between and divide by the number of courses of tiles taking into account minimum cover, however in this case I had two roofs, both with the same pitch but of different base width and different heights and I wanted to keep the courses in line with each other, so one optimum spacing was not necessarily OK for the other roof, a compromise was needed ? Some measuring, puzzling, swearing, mumbling and a few guesses later a compromise measurement was decided on, so now we could fix the battens.
A little trick I used here to maintain the spacing between battens was to cut several pieces of timber to the requisite length and use them between battens whilst fixing them. I am probably not the first to think of that one??
All the battens in line,very neat
 
Getting towards the ridge with the battens. Note the vacant area for the roof lights

Fixing the leading in the valleys. Another tricky job!

There are nine roof lights in this build so by the time I get to the last I should have got it sussed!! Not that difficult really, Velux have got it well engineered here, very well made with complete instructions but it was still with trepidation that I  put the first knife cut in the membrane. Should not have worried though and managed to fix four in a short space of time and I was ready for the first tiles.

You don't cut through a membrane like that without some worry.

Well that wasn't too bad
The tiles were next and I was determined that the roof should look professional although having said that I have seen some awful professional jobs,wiggly courses both up and across, uneven courses and cut verges. In order to avoid these obvious defects spacing of the tiles was critical (and difficult) and I used a builders line top to bottom to ensure the tiles were in line.
It was a small remark by my NHBC inspector but one that increased the amount of work dramatically, 'Get hold of a nailing pattern from the tile manufacturer' he said glibly. I did and in my area it required that all tiles should be nailed, with tile clips on two courses of tiles around all openings, eaves, ridges and verges and tile retaining straps on all verges. what!!!! you would think we lived in the wilds of Scotland and not the East Midlands but we had to comply to get our Solo certificate.

The first tile to go on and verge clips for every course of tiles
 


Our regular volunteer helpers









The completed front roof without roof lights, hopefully it looks as neat to you as it does me. The back roof with lights is not quite as I would like it due to the constraints of spacing around the roof lights themselves but it is more than acceptable.
Well just the small job of mortaring the verges, fixing the ridge tiles, leading around the chimney and fixing the beautiful Brett Martin cast iron effect rain ware and the roof is complete. Just like that!!

Next time on 'The Real Self Build Blog' I will tell you about the beautiful GlynnGary sash windows and how we fitted them.

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1 comment:

  1. Great to see these pictures! Hopefully we should be doing this in a fair few months. Nice too see your doing it mostly by your self. Thats what we hope to do!
    Please support me by taking a look at my blog, and possibly following.
    http://selfbuildwhitstable.blogspot.com/

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