proping up purlins

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maximus999

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Hi all again, as a recap i am going to convert my loft in a year or two time but i want all info to go down the best route. I know a structual engineer is needed as a must but want some ideas from you guys well before i proceed. The ceiling i have at the minute does not have the correct joist to lay a floor on so i am going to take all ceilings down and re-joist with 10x2 before i even start on any roof structures. I have a purlin support on each side of the roof which runs diagonaly onto the main joist which runs from the front to the back of the house, these i want to remove to open the loft right up. I have posted on here before about this problem with good ideas and results coming back, my question is: could i get 2 10x2 joists and sandwich them together with a metal plate say 10x 1/4" inbetween to support upright supports from the floor joists to the purlin to take the load?
As the purlin span is 18 foot long i am thinking of making 3 of these up for each side of the roof and for the rest of the joists which are not sandwiched still run vertical wood supports. I live in a 1 storey type cottage house and i want to try and stay away if possible from rsj beams as i have just replaced my whole roof. Thanks for any advise and sorry it is long winded.
 
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Why no steels? You realise steels for loftys are generally made up of say three seperate lengths and then spliced together in the loft space?
 
Freddy, i didnt know that, all i have seen is a hugh crane lifting the rsj beams up and through the roof. So you are saying i can get the beam split into three sections? if so are they bolted together or welded? this sounds interesting and a hell of a lot easier to do
 
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maximus999 said:
Freddy, i didnt know that, all i have seen is a hugh crane lifting the rsj beams up and through the roof. So you are saying i can get the beam split into three sections? if so are they bolted together or welded? this sounds interesting and a hell of a lot easier to do
Click to expand...

take into consideration the added cost of the splicing to the cost of a crane... in my opinion.. the crane is far the cheapeast option..
 
You would really struugle to get a flitch beam to work spanning 18 feet, and carrying roof and stud wall load. Certainly what you are describing wouldn't be sufficient...

*Edit* Do you mean three under each purlin :?: :eek: I guess that would do the job...:rolleyes:

Anyway...steelwork is the way to do it. As Freddy said, you can get the beams spliced. Endplate splices are much simpler and cheaper to do although some engineers don't like them.

Using steelwork you might then be able to span your new joists between the steels allowing you to use shallower joists and gaining a bit of headroom, somthing which is often an issue. Don't forget you'll also lose headroom when insulating under the roof.

If you've just replaced your whole roof I take it you aren't planning any dormers?
 
Thanks for the info guys, I am not planning on doing any dormers just veloux windows, All i want to do is support the wooden purlins that are in and take the purlin supports out. I dont know what way to go around it for the best, i have posted on here before and someone said i could support the purlins with uprights coming from the 10x2 floor joists and it was just an idea to beef up a few of the joists on either side of the house with metal plates in between. I will post some pics on here for you all to see. Many thanks for the info guys.
 
I dont have to remove the roof, i just dont want to cut the underfelt or remove the nailed in tiles thats all, in the pic with the dormer there is rsj beams in place, i am replacing the whole ceilings in my house with 10x2 for the ceiling and the strength for the new floor in the loft. i might just go with the original reply a year or so ago and put upright supports to the purlin from the new floor
 
Hi guys, just a quick update, there is a builder doing a loft conversion up the street from me. I have had a word with him and he said i cant put rsj beams in as my party walls are only 4 inch thick, he said i have to place a 9x2 from the footplate which will be tied into the floor joists, up to the ridge and one down the other side with a collar tie bolted at the top of each 9x2, he also said i cant put any loads over the windows or doors internally or externally, he said i have to run a joist (at the end of the floor joists either side of the window or door) between the floor joists and come of that joist for my floor joists. If that makes any sense. Anyone think this is a good idea, or is there any other way to support my purlin which is in place as he said the purlins and supports for the prulins totally come out and the roof is held counteracting each other the the 9x2 joists up each farter
 
There are usually several ways of designing new structures for loftys, employ a good SE and he'll have probably done several in your area anyway, find out who the SE is on this other lofty and if he's any good, if the builder isn't using an SE take everything he's said to you with a pinch of salt!
 
Hi guys,
i had an idea. As i cant put any loads over the windows, could i not put a steel reinforced lintel like the ones you put up above garage doors over the window opening to sit either side onto the bricks to take any loads onto the actual wall??
 
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