Steel in loft coversion

TrickyD

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Lot of loft conversions going on round here, latest one started a few doors away a couple of days ago. Out in the garden today trying to tidy my shed and I could hear exotic languages being spoken, and caught a glimpse of the people doing the extension. It's come on in leaps and bounds, but as yet, not seen any steels going in. These lofts are quite roomy, ours is just boarded, but got about 50 square meters of useable flooring, just for storage, not a room. Is there now no need for steels ? I know some planning regs have been relaxed, but will their house come tumbling down ?
 

Dave

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The only time I've not seen steel used is in modular constructions where the loft conversion comes pre-made and literally bolts onto the top of the house.
The strength is built into the design, similar to trusses. It is not possible to do this by converting original loft space.

You tend to get a minimum of two steel beams in a dormer conversion - one to carry one end of the suspended floor joists (the other ends sit onto the wall plate if building out to the perimeter wall.)
And a ridge beam for the existing roof spars to rest against and to carry the end weight of the dormer roof.

Other beams are used if the floor is not going to the building perimeter (back wall plate) and if the existing roof is high so two ridge beams are required.
 

mickthechippy

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I cant remember a loft conversion that an architech or enginer has not required steels, flitch beams etc

they always err on the high side of load weights,
 

RedhillPhil

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The only time I've not seen steel used is in modular constructions where the loft conversion comes pre-made and literally bolts onto the top of the house.
The strength is built into the design, similar to trusses. It is not possible to do this by converting original loft space.

You tend to get a minimum of two steel beams in a dormer conversion - one to carry one end of the suspended floor joists (the other ends sit onto the wall plate if building out to the perimeter wall.)
And a ridge beam for the existing roof spars to rest against and to carry the end weight of the dormer roof.

Other beams are used if the floor is not going to the building perimeter (back wall plate) and if the existing roof is high so two ridge beams are required.
That's exactly how and what was done in my house in Redhill.
 

Dave

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I cant remember a loft conversion that an architech or enginer has not required steels, flitch beams etc

they always err on the high side of load weights,
The last one I did the architect specified a beam for the floor support that would have been better holding the house up, never mind a floor :)
It had to be fabricated in sections and bolted together in situ, such was the size and weight of it
He also specified two smaller beams for the ridge which when put in place ended up about 300mm apart, whereas one beam would have sufficed.

But hey, ho, stick to the plans
 

Wise Owl

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Over the last 15 year ive done subbie work for a Loft conversion company doing 7 - 10 a Year not yet seen one without Steels.
 

Dave

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The problem is you could bolt together timbers in a laminate fashion to make the beams, and they would do the job. However as timber flexes it would sag under load in time unless you were going down the route of large beams, such as the size used for purlins, but nowadays the timber is not the same density and quality of old so unless you were going to use Oak or similar I'd have thought it would still allow too much movement.

Add on to that, an all-timber construction might hold the weight of the floor and roof as you're putting it together - but what happens afterwards?
No one can say how many people, furniture, etc will end up in the room after you've finished and gone, and likewise with the roof how much snow might fall on it, how strong the winds might be, and so on.
Do the job right the first time and it'll last long after you've taken your tools away.
 

Wise Owl

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Just to Add ive been to a Few where they had it Done without steels and we've put em right. The sights of Sagging Ceilings and some that have collapsed only costing more Money to put right.
 

Dave

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I did one once and the house next door had had a conversion done and the owner was a friend of mine.
He kept saying how well the guys who'd done his had done it, how we should... what we need to .... make sure we did.....

When we were putting the padstone in the party wall for the ridge beam it exposed the end of his beam - no padstone, no brick support, instead it was sat on a piece of floorboard spanning a gap filled with bits of broken brick and gobbo :D
The rubble had settled, the floorboard sagged under the weight, and I had the greatest pleasure in taking a few photos to show him how good his 'builders' had been :D

I put it right for him in return for a big slice of humble pie :D
 

mickthechippy

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The problem is you could bolt together timbers in a laminate fashion to make the beams, and they would do the job. However as timber flexes it would sag under load in time unless you were going down the route of large beams, such as the size used for purlins, but nowadays the timber is not the same density and quality of old so unless you were going to use Oak or similar I'd have thought it would still allow too much movement.

Add on to that, an all-timber construction might hold the weight of the floor and roof as you're putting it together - but what happens afterwards?
No one can say how many people, furniture, etc will end up in the room after you've finished and gone, and likewise with the roof how much snow might fall on it, how strong the winds might be, and so on.
Do the job right the first time and it'll last long after you've taken your tools away.
you can buy laminated non directional ply beams that apprently have the strength of steels, but as they run to the same sorta price as RSJ's they aint used much

they come from sweden, used a lot over there
 

mickthechippy

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Timbers gone downhill a lot since I first picked up a broom and teapot to start learning the trade

way back then, the majority of softwood used in construction, for first and second fix was "baltic" pine, either a red or yellow deal

it came from natural ancient forests, mainly around scandinavia or from canada, slow grown trees, which had a far superior density of timber to what is considered acceptable for today

the stuff that we use now, the majority of it is fast grown spruce, culled from young trees in those dark lifeless plantations that straddle acres of scotland and northern england

just picking it up betrays its worth, its far lighter and full of knots, looking at the end grain, shows ring growth with far wider annual markings and you can damn near crawl down the medullary rays,

back in the day, we knew it as packing or crating timber, and it was used for non structural purposes,
 

Wise Owl

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I did one once and the house next door had had a conversion done and the owner was a friend of mine.
He kept saying how well the guys who'd done his had done it, how we should... what we need to .... make sure we did.....

When we were putting the padstone in the party wall for the ridge beam it exposed the end of his beam - no padstone, no brick support, instead it was sat on a piece of floorboard spanning a gap filled with bits of broken brick and gobbo :D
The rubble had settled, the floorboard sagged under the weight, and I had the greatest pleasure in taking a few photos to show him how good his 'builders' had been :D

I put it right for him in return for a big slice of humble pie :D
Humble pie tastes Great dont it mate ? 2 houses were built at East Ardesley i plastered one out the other said he would Board the Studs and Ceilings and would i just Dry Line the walls and Tape and Fill. I said i didnt do that as it was not a good finish. He proceeded to get someone else, over the next year i went back as he cleared rooms to PVA and re skim the lot at a higher cost to what it would have cost him if the house was empty.
 

satinet

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New growth timber isn't the best that's true.
LVLs and gluelam wooden beams are pretty good. They are used a lot in the States. I think we have a ridiculous strange obsession with steels in this country. the specs things are made to often have no bearing to any sort of practical reality. Structural engineers seem to operate on a times it by 6 approach to loadings.

For the op - planning aren't really interested in how buildings are built beyond how it looks. Building control are responsible for ensuring legal standards are adhered to.
 

Maesknoll

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These guys could be worth a call, seems like a quality job of steel fixing.....

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