Loft - roof support change

[saabtastic]

Hi All

I want to improve my loft space, board it out/lighting/window etc but first need to get rid/move two cross supports from the loft space.

The house is a 1950's semi, brick built/including brick internal walls, with hip roof. The loft space is very open except for two cross supports each approx a third along the roof, consisting of 4x2 uprights (between roof rafters and ceiling rafters/joists) and a horizontal 4x2 cross member tieing the two together at 1.0m high. with diagonal bracing (v shape) to the ceiling rafters.


Obviously i would like to remove these two so that i have an unhindered open area. I propose to have vertical (4x2) supports at every rafter (0.3m spacing) tieing the roof rafters to the ceiling joists and purlins.Also placing 4x2 at approx 2m height at every roof rafter thereby tieing each side of the roof together (this gives a total 15 supports each side and roof)

With regard to the diagonal bracing i intend to to make the angle a little steeper and place a spreader block between them to give an easy/open area walk through.

This is all leading to a full conversion later on, but at the moment i just need an open storage area, but i might as well add supports at this stage rather than later.

Do you think this is acceptable or over engineered, just don't want the roof to sag, hopefully it will not with all the extra support compared to what is there.

many thanks
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[masona]

Hi All

I want to improve my loft space, board it out/lighting/window etc but first need to get rid/move two cross supports from the loft space.

What do you want to use the loft room for because there're planning and building regulations issue.

The house is a 1950's semi, brick built/including brick internal walls, with hip roof. The loft space is very open except for two cross supports each approx a third along the roof, consisting of 4x2 uprights (between roof rafters and ceiling rafters/joists) and a horizontal 4x2 cross member tieing the two together at 1.0m high. with diagonal bracing (v shape) to the ceiling rafters.

I really need to see a photo as these timber do an important part of the roof.

Obviously i would like to remove these two so that i have an unhindered open area. I propose to have vertical (4x2) supports at every rafter (0.3m spacing) tieing the roof rafters to the ceiling joists and purlins.Also placing 4x2 at approx 2m height at every roof rafter thereby tieing each side of the roof together (this gives a total 15 supports each side and roof)

I'm afraid it's not straight forward as it will need new bigger joists along the side of the ceiling joists.

With regard to the diagonal bracing i intend to to make the angle a little steeper and place a spreader block between them to give an easy/open area walk through.

You can not altered the design of the roof unless it's made wrong

This is all leading to a full conversion later on, but at the moment i just need an open storage area, but i might as well add supports at this stage rather than later.

You will need to put in bigger joists in first before you do anything unless your stress load calculation can take the weight of RSJ instead.

Do you think this is acceptable or over engineered, just don't want the roof to sag, hopefully it will not with all the extra support compared to what is there.

The roof will sag if not done correctly, I would say your best bet is have a drawing plans done for a piece of mind, cheaper in the long run
I'm not trying to fighten you but I have been to many rush job to support the roof temporary because they've taken out the timber in the way etc.

 

[Static]

99.9% of roof structure is load bearing in most roofs so removing stuff is not a good idea unless you know what you are doing.

Photos would help, but from the description it sounds like you have a purlin supported roof with diagonal braces every rafter? and you want to remove these braces? or are there only 2 of these braces in the whole loft?

 

[saabtastic]

Hi, thanks for your swift replies

The loft is for storage at the moment--pull down ladder etc

Yes there are only two sets of these supports, consisting of 2 verticals (1 each side) 1 horizontal beam and the v shape bracing. (so not a lot of support really !!)

i intend to place vertical supports at every rafter position tieing the roof rafters to the ceiling joists-also nailed to the purlings to tie it all together. Giving a total of 15 each side vertically. I am also doing the same horizontally at the roof rafters ( at 2.2m height) again 15 in total. this should brace the roof more than it is now.

i was also going to strengthen the ceiling joists with some 4x2 lengths (3.0 clear span) and bolt these to the existing 4x2 joists, also bolting to the purlins. I have brick wall running the length of the loft below the ceiling joists which will also give some support hopefully.

many thanks
john

 

[masona]

i intend to place vertical supports at every rafter position tieing the roof rafters to the ceiling joists

Can't do that, the ceiling joists will bow therefore the roof could collapse

 

[Static]

Sounds like the diagonal members brace the purlins and probably transfer the purlin load down to a load bearing wall (still need some photos to be sure). Putting in verticals may not be the answer as they will transfer the load onto previously unloaded members, even with the additional members the result will probably be cracks in your ceilings.
Still would need more photos/info to come up with a better option

 

[saabtastic]

Hi
the diagonal bracing is not supported onto a wall, there are offset from each other--that is the bottom of the "v", they are just nailed to a ceiling joist. There is a wall running the length of the house-at aprox the centre of the house, this is obviously giving support to all the ceiling joists.

But surely taken out 4 vetical supports and putting in 30, in fact i am not taken out the original 4, just supplementing them.

The main concern is the diagonal bracing, as i said b4 i intend to keep some bracing-slightly steeper angle with spreader beam between them to give a clear route(giving a wide U shape). The two horizontal members will be replaced with 15-although at a higher position.

Maybe it is time to get a structual guy in.
cheers

 

[Static]

Maybe it was just badly described, as ive said photos/sketches help alot. But from what i gather you intend to alter the whole structural nature of the roof. Get a structural engineer to look at it as you intend to convert the loft space anyways you would have to do this in the end.