extending a fibre cement roof (wrong way for lap)

dannewhouse

Member
Location
huddersfield
i have a shed to extend but the roof sheets were laid from the end I want to extend on to the opposite end I just wondered if anyone had come across this before I'm sure some contractors will have.

my 3 thoughts were:

1. lay the roof underhand ie the wrong way around by hooking the next sheet under all the time, sounds difficult to me.

2. lay as you normally would but hook the 1st sheet over the top of the hook of the old sheets (I know these wont fit perfect together but will they be that bad?)

3. put an expansion joint joining the 2 and just start 1" away from the existing roof.
 
i have a shed to extend but the roof sheets were laid from the end I want to extend on to the opposite end I just wondered if anyone had come across this before I'm sure some contractors will have.

my 3 thoughts were:

1. lay the roof underhand ie the wrong way around by hooking the next sheet under all the time, sounds difficult to me.

2. lay as you normally would but hook the 1st sheet over the top of the hook of the old sheets (I know these wont fit perfect together but will they be that bad?)

3. put an expansion joint joining the 2 and just start 1" away from the existing roof.


Usually just number 2.

How long is the building now?
 

dannewhouse

Member
Location
huddersfield
the existing is 120ft
when I've finished (try to extend by 60ft every couple of years as funds allow) the building will have another 30ft on the "correct" end and 150ft on this end but I'm only putting 60ft up this year. (I like to know exactly what I want the yard like so I don't end up hemmed in a corner like most farmyards!)

I know they recommend an expansion joint for this length but do they really need one? I think they look ugly but cracked sheets will look worse!
 
the existing is 120ft
when I've finished (try to extend by 60ft every couple of years as funds allow) the building will have another 30ft on the "correct" end and 150ft on this end but I'm only putting 60ft up this year. (I like to know exactly what I want the yard like so I don't end up hemmed in a corner like most farmyards!)

I know they recommend an expansion joint for this length but do they really need one? I think they look ugly but cracked sheets will look worse!


For what it is it might be worth putting an expansion joint in
 

Nose Abit

Member
I thought that as in total it will be a 300ft shed but you don't often see them do you?
Use an expansion/movement joint. Up to 45m you don't need them, 45 - 75m the roof should have 1 joint and from 75 - 105m it should have 2 joints, so eventually your roof at 300ft should have 2 joints. Now is the ideal time to put one in and it will make sheeting a whole lot easier.
 

dannewhouse

Member
Location
huddersfield
seems daft that a 45m shed wouldn't have a movement joint but a 90m would have 2,
marley eternity list movement joints but briarwood don't seem to bother?

do you do a 345 triangle triangle to square your roof?
and do you seal 150 mm laps on a 15 degree pitch? it seems to be a bit on the changeover but the existing isn't sealed.
 
seems daft that a 45m shed wouldn't have a movement joint but a 90m would have 2,
marley eternity list movement joints but briarwood don't seem to bother?

do you do a 345 triangle triangle to square your roof?
and do you seal 150 mm laps on a 15 degree pitch? it seems to be a bit on the changeover but the existing isn't sealed.

Just measure your sheet off your rafter to get it square.

Or if you're not confident put a string line at bottom
 

dannewhouse

Member
Location
huddersfield
Just measure your sheet off your rafter to get it square.

Or if you're not confident put a string line at bottom
I do both, jus wondered what others do. but did a roof for a neighbour in metal profile I thought that was a lot harder to keep square than fibre, every time I knelt on the sheets they expand slightly and blooming fixings I was fed up of them! 3 per purlin or 6 on ends and rooflights whats wrong with 2 and 4 for rooflights! it was only a 20ft wide building so its probably easier to keep metal square on longer roofs.
 

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