Hello all, i've got an extension underway and its time to tackle the roof - mono pitch, 17deg, Marley Modern tiles on 38mm x 25mm battens, 170x50 roof spars, breathable membrane. A couple of basic questions how should the membrane be attached to the spars? does every row of tiles need nailing? what size nails for these tiles (50mm)?
New extension roof, basic questions.
- Thread starter redlee
- Start date
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im no roofer nor no builder BUT, with my roofing problems at the mo, the roofer has nailed every tile making it very hard to simply slide and pull out incase of problems in the future. I thought roofers generally nailed a row and then left the next 2/3 rows un-nailed and then the next row nailed etc but i suppose this theory is very much dependent on the kind of tile your using.
Andy
Ok no nails needed?
Pull the membrane tight or sag and if sagging how much?
Spars are at 400mm centres and building control want 70mm kingspan interspacing and 50mm overboarding.
Pull the membrane tight or sag and if sagging how much?
Spars are at 400mm centres and building control want 70mm kingspan interspacing and 50mm overboarding.
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If the roof is exposed near the coast or on a hill (ie in a severe exposure area) you will need to nail & clip every tile at such a low pitch.
In less exposed areas clipping every other diagonally is usually sufficient.
If you not exposed at all - say back yard lean-to away from the coast - then clips and nails become less essential.
Pull the felt reasonably taught, but don't stretch the fixings, it will naturally sag enough to allow sufficient drainage.
Over-rafter kingspan? then you will require counter battens which may mean and upgrade on fixing spec! dependent on location.
In less exposed areas clipping every other diagonally is usually sufficient.
If you not exposed at all - say back yard lean-to away from the coast - then clips and nails become less essential.
Pull the felt reasonably taught, but don't stretch the fixings, it will naturally sag enough to allow sufficient drainage.
Over-rafter kingspan? then you will require counter battens which may mean and upgrade on fixing spec! dependent on location.
R
RedHerring2
Redlee, you need to clarify, is the overboarding above or below the rafters?
The greater the pitch the greater the need for nailing not t'uther way round.
Apologies by overboard i mean underline (under rafters).
It is a rear lean to south facing close to neighbours so well sheltered. Is it ok to cut the bottom of tiles to fit around the top of a velux?
Not strictly true; when pitches get above 45 degrees then each tile needs to be fixed, but the vast majority of roofs are between about 17 and 45 degrees and it is true that the lower pitches require more fixings; it's all about the wind suction effect; the same force that keeps aeroplanes up.
Just to be absolutely clear - at this low pitch then more fixings are required - not less!! and as previously stated; if its exposed then every tile will need to nailed and clipped.
Oops, just read the bit about the roof being not at all exposed so fixings not such an issue after all.
As far as cutting the bottom off the tiles is concerned: It is much better to keep the bottom of the tiles on, so lift the tiles behind the skylight higher, i.e put a batten in further up to align the tiles so the bottoms run through at the correct height. You will probably still need to cut the corner ones though unless your lucky (or you've worked it out very well!)
As far as cutting the bottom off the tiles is concerned: It is much better to keep the bottom of the tiles on, so lift the tiles behind the skylight higher, i.e put a batten in further up to align the tiles so the bottoms run through at the correct height. You will probably still need to cut the corner ones though unless your lucky (or you've worked it out very well!)
If i move the batten up it means the last couple of rows will have a massive headlap from memory over half a tile - is this ok?
At that headlap the tile will probably kick up. It will be a cut.
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