loft conversion answers

cyclonebri1

leveller2911 wrote: »

Qualified Joiner & Carpenter making Joinery and also traditional cut & pitch roofs,eyebrow windows,Mansard roofs,Sussex barn Hips,gables,dormars etc.


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If you were a structural engineer you wouldn't have jumped to conclusions based on little or no evidence and would have called them by their proper names (Purlin,struts and binders).

I wonder if thats how some structural engineers make their money......

By scaremongering/frightening people based on little information.

My advice to the OP is get it checked out for piece of mind if nothing else.

Show me 1 roof structure where you can take out support struts and reposition them "elsewhere" without strengthening "elsewhere" and I'll concede to any little exception to the rule you are so desperate to find.


And before you go off on one again you may want to read again, more closely this time, what I actually said in the post that seems to have given rise to your Mr Hyde side, I said;

Quote......"The mega question is whether the floor joists were strengthened, if they weren't then it's not a case of getting any money back, more 1 of have you actually devalued the house., sorry, just being blunt."



I didn't say they had, I clearly said may have just opened the possibility to the OP.

You may well be a master joiner, good on you, but read before typing next time.


I apologise to the Newbie 1st time poster, the options where given for your benefit, I can't help it if another poster wants you to bury your head in the sand with regard to the worst possible scenario.:(:(:(

cyclonebri1

FilthyLuka wrote: »

I always thought binders were to break the span of ceiling joists; I've never seen them supporting the rafters.

That's exactly what they are for, simply to prevent lateral movement of the ceiling joists in a conventional roof construction, they are not designed to carry load from the rafters. This can be done in a loft conversion but what will now be new floor joists will have to be placed 1st to carry the load of the stud walling, the purlins, which are very likely to need up rating, carry all the roof load at above eaves level.

mysk_girl

I am a structural engineer and recently converted my own loft. As the house was built in 1890 there was enough redundant and oversized timbers already in place to negate the need for any additional strengthening. We removed the central truss and re supported all the rafters onto the ceiling (now floor) joists. All proved by rigorous calculation, and signed off by building control. There is your exception!

But, it is an exception and most definitely not the norm.

If I were a buyer, I would expect my survey to pick this up and further questions to be asked. They may ask for a structural engineers report to look at the joists and alterations. I agree that, in general, joists designed as ceiling joists are not normally suitable for floor loading but there are too many variables to give a definitive answer.

cyclonebri1

mysk_girl wrote: »

I am a structural engineer and recently converted my own loft. As the house was built in 1890 there was enough redundant and oversized timbers already in place to negate the need for any additional strengthening. We removed the central truss and re supported all the rafters onto the ceiling (now floor) joists. All proved by rigorous calculation, and signed off by building control. There is your exception!

But, it is an exception.

If I were a buyer, I would expect my survey to pick this up and further questions to be asked. They may ask for a structural engineers report to look at the joists and alterations. I agree that, in general, joists designed as ceiling joists are not normally suitable for floor loading but there are too many variables to give a definitive answer.

Indeed, which is why my original post said may have rather than will have, a subtlety that missed someone.

The total intent of my post was to make the point that a loft conversion done on the cheap and without any form of control or deep understanding, will be flawed, and the most likely flaw and the one that every thing else is built on is the sizing of what become floor joists. Given that the whole lot has to come out for it to be used safely.

leveller2911

FilthyLuka wrote: »

I always thought binders were to break the span of ceiling joists; I've never seen them supporting the rafters.

Whats the condition of the ceiling of the room below the loft conversion? If its showing signs of cracking to the plaster theres probably a structural issue

Building regs would have been needed for a loft conversion and theres a good chance that theres issues with unauthorised conversions. Did anyone advise you at the time about them as this is often an issue when selling.

Was is a bungalow or a 2 storey house or more before the works? Do you have fire doors and mains smoke detection?

As you say binders are there to break the span of the joists,far easier to fix gyproc sheets to joists that are straight but I never stated binders were there to support any weight, they are also a fixing point for the purlin struts which help support the rafters.The binders are not always over a structural supporting wall but can be.

What I was saying was the OP hadn't given enough information to conclude that removing the struts and forming an ashlar wall would mean the roof was dangerous which is what Brian was posting its only on fairly modern roofs that you find ceiling collars fitted on every pair of rafters and bolted through but go back 40yrs and you tended to get ceiling collars on every few pairs of rafters just nailed on.As an example there may well be more than one supporting wall under the binder so its quite possible the new ashlar wall was positioned over a supporting wall.Another example is in the old days the Purlins were huge compared to todays roofs and not uncommon to see 12x4 or 9x4 purlins built into the gable walls at each end with no strutts or binders needed.

leveller2911

cyclonebri1 wrote: »

Show me 1 roof structure where you can take out support struts and reposition them "elsewhere" without strengthening "elsewhere" and I'll concede to any little exception to the rule you are so desperate to find.


I'm not desperate to find exceptions ,as I keep saying the Op hasn't given enough information for you to conclude anything.I can show you many roofs where timbers were nailed on that were either not needed,in the wrong place or undersized.The key information that we don't have is where exactly is the structural supporting wall positioned that takes the weight of the roof.There can be more than one supporting wall in a house.You don't know the dimensions of the joists,purlins etc.Dependant on these may mean that ceiling collars bolted to each pair of rafters should have been fitted, may mean that the joists should have been strengthened (as you mention) but the point is we don't know.







You may well be a master joiner, good on you, but read before typing next time.

I'm not a Master Joiner or Master Carpenter, just a Carpenter & Joiner. Is there more money in being a "Master"?..:D


I apologise to the Newbie 1st time poster, the options where given for your benefit, I can't help it if another poster wants you to bury your head in the sand with regard to the worst possible scenario.:(:(:(

At no time have I encouraged the OP to "Bury their heads" I suggested they got an engineer in to check.Some people on here are too quick to jump to conclusions. Guess we will have to differ on this one.Maybe my posts don't always read as they are intended guess thats the internet for you.

Good luck OP hope you get it sorted, always a good idea to get proposed structural work checked over before you start.

cyclonebri1

I think we frightened off the op a while back, but as usual it's a case of each of us trying to fill in the blanks in the absence of full information, I know what I'm talking about and I'm sure you do too, but we each have a different scenario in view though;)

Naf

Can I cheekily ask a quick related question?
These types of 'conversion', where its essentially boards placed onto the existing ceiling joists; how much 'stuff' are they suited to holding? I mean are they sound enough for a decent number of boxes of stuff. Some people have suggested to me they can be used as offices? I just want to put a load of boxes of stuff into mine - but probably quite a lot of boxes...
Hope you don't mind the brief hijack, OP...

cyclonebri1

Use common sense, don't pile all the boxes up near the hatch because it's easiest.
Place them around the loft spreading the load as far as possible and keep to the ends of the joists rather in the centre where you are most likely to cause bowing. Be aware of where your intermediate walls are below, these should offer support.

I don't think anyone will give you a weight figure, just a recommendation to use your brain, the loft is there as a divider between living space below and the cold area above, not as heavy duty storage.

It also depends what you are storing, clothes, toys and general stuff is all ok, if it's the contents of a closed engineering shop then take care, I'm sure you get my drift;);)

2 points, ensure you keep boxes sealed and dry, condensation hence rust can be an issue.
And ensure you do not block the ventilation route through the loft, in particular at the eaves.

And yes, put boards down 1st, very easy for something to fall between the joists. If it's just storage, don't bother to fasten them down, they may/will have to come up for electrics etc.

homeowner67

I get too busy to come back for a few days and people make the replies all complicated, and all hell breaks loose! It's a bungalow loft. There were 6 diagonal loft braces in a pitched roof, the tops were joined on horizontals, each side of the roof then the bottoms meeting in the middle and we left 4 in. (can't find a link to a pic) We didn't put in stairs. My partner said if push comes to shove he'll have to put them back in. We didn't pay the builder as he is a friend of ours, likewise the electrician and the plumber, so no money lost really. we have taken away the ladder and put a loft hatch in as that is what we were advised to do for now. If a buyer comes and when they have survey we will find out won't we!