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Moggaman

Difficult roof???

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Hi. I would appreciate any input. I am fretting about the build ability of my roof. It is a straight v roof but because it is room in roof, there are large spans.. I will talk to an engineer but am just trying to get an idea.. will I definitely need I beams running the length of the house to support the roof?

thanks

 

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Worth speaking to an SE 

Normally you would add a steel to the ridge and build a cut roof off this 

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Similar spans to our house. Central steel ridge beam and 250x50mm joists at 400m cc for the cut roof. In the end we went with an insulated panel system. We have secondary 150mm joists at the suspended ceiling to stop the panels spreading. Can't remember the name but similar to purlins but they don't bear on anything... Just braces the two roof halves together at about 1m down from the ridge. Btw why 2400mm ceilings? May as well vault fully or go to at least 2700mm. Will make it feel much bigger.

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1 hour ago, Conor said:

Similar spans to our house. Central steel ridge beam and 250x50mm joists at 400m cc for the cut roof. In the end we went with an insulated panel system. We have secondary 150mm joists at the suspended ceiling to stop the panels spreading. Can't remember the name but similar to purlins but they don't bear on anything... Just braces the two roof halves together at about 1m down from the ridge. Btw why 2400mm ceilings? May as well vault fully or go to at least 2700mm. Will make it feel much bigger.

Thanks Conor... the reason I went 2.4m was that I thought it might need to be braced as low down as possible. Can I ask, the ridge beam, it will bear on the block gables at the end.. my house is 12.5m in length., they will require supporting I presume 1/2 way..what did I support on ..

2nd, did your rafter need intermediate support from the ridge to the wall plate...5.23m is my longest distance from the ridge to the wall plate . Thanks . I appreciate the response.

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10 minutes ago, Moggaman said:

Thanks Conor... the reason I went 2.4m was that I thought it might need to be braced as low down as possible. Can I ask, the ridge beam, it will bear on the block gables at the end.. my house is 12.5m in length., they will require supporting I presume 1/2 way..what did I support on ..

2nd, did your rafter need intermediate support from the ridge to the wall plate...5.23m is my longest distance from the ridge to the wall plate . Thanks . I appreciate the response.

Yes. our house is 13m wide and ridge rests on two intermediate block walls. I think only 1 was required tho. NB likely a ridge beam will come in shorter lengths and be spliced together on site so you'll likely need at least one intermediate support wall.

 

Our ridge to wall plate is just under 5m.

 

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19 minutes ago, Conor said:

Yes. our house is 13m wide and ridge rests on two intermediate block walls. I think only 1 was required tho. NB likely a ridge beam will come in shorter lengths and be spliced together on site so you'll likely need at least one intermediate support wall.

 

Our ridge to wall plate is just under 5m.

 

Conor, see below plan. The purple arrows point to block walls which run from one gable to the other. This wall is sitting on wideslab precast flooring. Could I bring the block wall all the way up to the level of the ridge beam and then fix a wall plate to the block wall. This would only be another 700mm extra in height. This would mean it would be supported all the way across the house. I could use lightweight block also if the loading was too much?. This wall (gable to gable) is also buttressed by other walls.. cheers 

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HI @Conorwhat size steel did you SE spec for the ridge , architect has suggested binning the trusses and going for a cut roof i can get the spans for glulam and work out a rough price but cant seem to find a steel span table and yous is similar to what i would need .

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Is there any reason you can't build that other wall up to match and go for a standard attic truss option - it would save you so much money and agg?

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Posted (edited)
29 minutes ago, Buzz said:

HI @Conorwhat size steel did you SE spec for the ridge , architect has suggested binning the trusses and going for a cut roof i can get the spans for glulam and work out a rough price but cant seem to find a steel span table and yous is similar to what i would need .

203*133*30 UB. max span between supports is about 5m

 

@Moggaman sorry, a bit beyond my knowledge I'm afraid. It would all depend on what loads the floor is designed to take.

 

Edited by Conor

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Just now, Conor said:

203*133*30 UB. max span between supports is about 5m

Cheers mate , gives me a good idea and can work out a rough price before i spend 1k on an SE and then decide trusses it is 😂

 

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There's lots of options to do this, but all of them need a structural engineers input!

If you've got a wall on the centre line it would seem a bit strange to then put a full length ridge beam above it... easier to get the guy with the insurance to design it than asking what size of beams others have used 😂

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Attic trusses?

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45 minutes ago, Faz said:

Is there any reason you can't build that other wall up to match and go for a standard attic truss option - it would save you so much money and agg?

I’m not with you?.. 

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16 minutes ago, the_r_sole said:

There's lots of options to do this, but all of them need a structural engineers input!

If you've got a wall on the centre line it would seem a bit strange to then put a full length ridge beam above it... easier to get the guy with the insurance to design it than asking what size of beams others have used 😂

I agree .. I am meeting him later this week but want to figure out some options in advance ...why would it be strange to put a full length ridge beam above the wall? I’m suggesting bringing the wall up to within 150mm of the ridge, fixing a timber beam onto the wall to take fixings from the 9 x 2 rafters that sit on it. Wouldn’t the roof load be spread across all of the upper floor . The ceiling joists of room would need to be fixed to the block wall either side though..unless the odd ope is left in the blockwoek?

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35 minutes ago, Moggaman said:

I agree .. I am meeting him later this week but want to figure out some options in advance ...why would it be strange to put a full length ridge beam above the wall? I’m suggesting bringing the wall up to within 150mm of the ridge, fixing a timber beam onto the wall to take fixings from the 9 x 2 rafters that sit on it. Wouldn’t the roof load be spread across all of the upper floor . The ceiling joists of room would need to be fixed to the block wall either side though..unless the odd ope is left in the blockwoek?

 

He's the skilled professional, you won't figure out any viable option without his input, that's what you're paying him for 😉 - talk to them about the options as they'll have all the information to hand to advise you properly. 

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