Any builders/architects? I'm trying to avoid my roof caving in..

platypus · 12 Nov 2012 at 14:08

This is my loft as it currently stands, if you can pardon the atrocious diagram.

Side view:

Essentially in blue is a sort of A frame, that doesn't really appear to be doing anything. It's secured to some floor joists, but at the top doesn't appear to be massively safely secured - eg its not support much of the roof weight at all.

There are two large joists running the length of the roof below the horizontal "a-frame" beam, and it seems to be these that the roof joists are taking their support from.

I'd like to make the space more useable, so want to take the Aframe out, and am wondering if adding two more supporting joists higher up will suffice - I've had a builder look at it and say that it will, but I just want to run it by the DIY experts on here and see what they think:

(roof face head on view)

As I'd like the roof to still be standing after taking it out

.

justalex81 · 12 Nov 2012 at 14:13

altering the structure of a roof is not a DIY job and should be done by a professional.

bitslice · 12 Nov 2012 at 14:15

You have a large blue stickman holding up your roof.

I would be worried too.

King Damager · 12 Nov 2012 at 14:15

Get a structural engineer to look at it.

kd

platypus · 12 Nov 2012 at 14:16

King Damager said:
Get a structural engineer to look at it.

kd

You would not trust a professional builder? Not trying to antagonise, just find out

.

K.C. Leblanc · 12 Nov 2012 at 14:17

justalex81 said:
altering the structure of a roof is not a DIY job and should be done by a professional.

It also might well require building control notification and inspection.

platypus · 12 Nov 2012 at 14:19

When I say I want to take the Aframe out, I'm more than willing to have it taken out .

Have already checked with building regs, as long as I'm not having the roof facade altered or made higher, it won't need permission/notification.

Raymond Lin · 12 Nov 2012 at 14:20

You'll need building reg for this.

platypus · 12 Nov 2012 at 14:22

Raymond Lin said:
You'll need building reg for this.

Hmm, the council planning department say we don't?

Raymond Lin · 12 Nov 2012 at 14:24

Are you sure they didn't just say you don't need planning or specifically building reg?

platypus · 12 Nov 2012 at 14:25

Raymond Lin said:
Are you sure they didn't just say you don't need planning or specifically building reg?

They said we do not need either because we are not adding a bedroom, but I understand what you're talking about now, I've quoted the wrong thing

.

Yes we will likely need building reg approval then. Bugger.

drunkenmaster · 12 Nov 2012 at 14:38

You want a qualified builder to look it over, far more than some advice from this forum with bad pictures.

Buildings can be made incredibly differently with the same outwards appearance, or built badly and therefore need other things doing to make safe, who knows.

Not in all situations but, a lot of pitched roofs the bits between the roofs are less about support and more about preventing lateral force, the support comes from the walls but pitched roofs, well think of two cards leaning against each other in the same shape, the bottoms of the cards want to move outwards. So the wooden structure inside is to keep them together, while the weight of the roof itself is loaded on the walls.

No matter how the roof is built, this is a job for a professional builder, and having a professional tell you what you can safely do.

Hagar · 12 Nov 2012 at 15:37

Removing the internal truss members will alter the loads on the rafters and walls. One option would be to run steel purlin members wall to wall under the rafters at the same height as the horizontal blue members. The upper purlins could then support a ceiling level and the lower ones vertical walls. You would need four steel beams (possibly large twin timbers to span the length of the roof. Built in at the gable walls. You have two of these members but they probably have lateral restraint from the horizontals in the frame.

This is a structural engineering calculation as you have to consider not only roof dead weight but environmental loads, wind, snow etc. to the current design codes. You also need to consider changes to the support at the gables, deflections under load and additional or changed support to the rafters on the wall plates. The A frame may well support the ceiling joists below.

A builder will tell you what is possible but for building regulations (not planning approval) you will need calculations submitted.

I am a civil design engineer by profession.

Maccapacca · 12 Nov 2012 at 15:43

You need a structural engineer to design steel beams for you, last one I used cost £250 for a visit and a sketch, it's pretty simple and an every day conversion.

If you want it to be liveable you would need building reg approval for things like fire between lofts (assuming it's semi or terrace) and also any stairs you put in will need to be signed off, head height, width etc, you won't need to if you're going to put your choo choo trains on a bit of plywood.

platypus · 12 Nov 2012 at 16:11

We have had a builder look at it, but from the sounds of it a structural engineer needs to be booked as well. I guess it isn't the kind of thing you can do on the cheap!

Firestar_3x · 12 Nov 2012 at 16:14

Had a very quick Google, take a look at this, page two in particular.

http://www.tra.org.uk/assets/file/pds8.pdf

platypus · 12 Nov 2012 at 16:43

That is indeed useful. Cheers.

apeksdiver · 12 Nov 2012 at 16:55

If you are looking to open the space up then steel joists will be the way to go. I guess you will still be using a ladder to access it? You will only need to keep the building regs people happy if you are converting it to a living space and will require fire doors everywhere and a mains powered integrated fire alarm system with sensors in every room.

platypus · 12 Nov 2012 at 16:59

apeksdiver said:
If you are looking to open the space up then steel joists will be the way to go. I guess you will still be using a ladder to access it? You will only need to keep the building regs people happy if you are converting it to a living space and will require fire doors everywhere and a mains powered integrated fire alarm system with sensors in every room.

Ideally we'd like to use it as an office. It won't however be a bedroom; does that qualify as a "living space"? If so we might can that idea and open it out for better/easier storage.

King Damager · 12 Nov 2012 at 17:28

platypus said:
You would not trust a professional builder? Not trying to antagonise, just find out .

Depends what you mean by professional really.

Are we talking a builder who actually has a good grasp of structural engineering, or just your average builder?

kd

Any builders/architects? I'm trying to avoid my roof caving in..

Tea Drinker