Loft space convert for clean light storage area

[oldman2]

I would like to utilise my central loft area for clean storage of clothes, shoes, toys etc. I have recently had a combi boiler fitted downstairs so there are no longer any tanks or pipework in the loft and the landing airing cupboard can be removed and spacesaver stairs fitted for ease of access. I dont wish for this to become a habitable room but just need more clean light storage area.

Here are some pics of my loft showing the layout of the joists, purlins etc

View media item 4366 View media item 4367 View media item 4368 View media item 4365
Timber sizes are as follows, Joists and rafters are 4x2" at 16" centers, Purlins are 3x5", Binders are 4x2" with 4x1.5" collars above them. There is a central load bearing wall below the loft running the same direction as the purlins. From Joists to ridgeboard I have 2.2mtr headroom.
The center area of the loft inside the purlins is 6.2mtr x 3.1mtr with 1.85mtr each side of this outside the purlin line to the outer wall plates.

I would really like to be able to relocate the binders and collars and board out the center section. What would be the most cost effective way of doing this?

I have removed a lot of very old insulation and rewired so no cables are on top of the joists in the center area since taking the pics, I need to re insulate but until I can figure whats happening with the struts etc I want to wait as I would like to preferebly isolate this clean area from the cold roof side by insulating the rafters instead where possible.
There is a chimney stack in the loft but this should be coming out soon as it was only for the old kitchen boiler.

I think thats enough info from me for now

 

[noseall]

your roof is almost identical to mine!

the components have been kept as minimal or as small as possible therefore all the roof 'elements' rely upon each other - in harmony if you like.

i have a pair of twin collars with bolts through the connections and have to duck each time i pass by them!

i'm sure an s.e. could design something to deal with the removal of certain elements of the roof but don't be surprised if it involves some big replacement timbers or even steel.

 

[oldman2]

I was hoping for some more feedback on this with maybe even a reply from one of the SEng who visit the forums.

Dont really want to get a structual engineer in just yet until I have half an idea if its likely to be in my cost range or unrealistically expensive for storage.

Bumping it in the hope...

 

[chappers]

From my experience doing loft conversions, what you propose would probably involve going half way to a full conversion. To remove the collars and purlin supports would invove some beefy steels or even bigger timbers running gable to gable with stud walls built up to support the purlins

 

[Shytalkz]

If you want to remove the diagonal struts, then the choices you have are to: strengthen the purlin to enable it to span the increased distance (bearing in mind that it bends about both axes, when placed at right angles to the roof slope); to provide vertical props at the same positions, but this will require some strengthening at ceiling level to take the prop load; or to construct a stud wall which renders the purlin redundant and again requires strengthening of the floor or the use of a steel or flitch beam above the existing joists.

The raised collars are less problematic and can be removed, once the purlin issue is resolved by the first and last above methods, but not for the vertical prop alternative, as there are horizontal forces applied to the top of the props, which the posts themselves (without some clever structural jiggery-pokery) won't sustain.

Doing this work, you're halfway to a "proper" conversion anyhow, so why not make the floor strong enough to take domestic floor loads? If you really don't want to do this, for the storage you suggest, the existing will be ok, providing that you deck it out and screw the boarding down at fiarly close centres. Any heavy stuff should be stacked as near as possible to support positions for the joists.[/list]

 

[oldman2]

Many thanks for the reply Shy, would I be right in thinking that beefing up the 5x3 purlins would be the cheapest option to enable removal of the struts & collars?
If so would I be able to "flitch" these to cut the weight/cost of strengthening them, each is 2 parts bolted together mid way along its length atm. I am again assuming that when flitching the new components don't have to be one piece eave to eave as that would be one long piece of steel plate!
If this is a possibility then a light stud wall could be constructed to divide off the dirty from clean areas of the loft space.

I'm hoping to have a kitchen extension built next so really don't have the spare money to consider a proper full loft conversion but could still use the clean loft space.

If the above is impractical the wife and kids will have to learn to limbo

 

[Shytalkz]

If the purlins are strengthened adequately, then the props and ties can be removed. This can be done either by a flitch arrangement, or by bolting a channel section to either or both sides of the timber purlin. The channels can be split to ease installation, but need a proper bolted connection where they are to join, to effectively make it a continuous section. The channel/s should also bear into the walls each end. You could of course use timber, but the required section sizes would be humongous.

A flitch plate can stop short of the walls, providing that the bolt arrangement here is sufficient to transfer the loading into both the existing timber and any new ones. The plate needs to be continuous though and connecting sections of this per the channel option is not easy to achieve.

Personally, I would probably go the channel/s route and split them at no greater than 1/3 span from the support.

If you really are only intending to use area this as light storage, are the props and collars really that much of an issue to step around?

 

[oldman2]

Shy, Thank you very much for your replies to my questions in this topic.

I really do only want the floor area of the loft for storage, the wife and 2 teen daughters seem to have turned into Emelda Marcos's with the amount of shoes, clothing and general chattles they have aquired. I have recently rewired the whole house and had new complete central heating fitted and in order to do this have had to remove most things from all the upstairs rooms to lift flooring etc. I now have black bags full of clothing etc that must have been somewhere before I started but the house must have shrunk while I was working on it!.

So its either let them loose in the loft area which needs then to be sealed off enough to be always clean of the general dust and dirt that seems to blow into the area now.
Or I need to invest in a log cabin/shed for their storage, the disadvantage of this is the gardens large but the location would be well away from the house.

If I were to do the work myself as a guesstermate would £1000 be likely to cover the costs of the purlin steelwork needed bearing in mind the roof is clad in concrete interlocking tiles on underfelt.

As this work is bound to be notifiable for planning should I talk to a SE next or should it be done through an Architect?

 

[Shytalkz]

If that's all the reason you want the space for, I would leave the props and collars and chipdeck the existing joists. You could build a little stud wall up behind the purlin, off the boarding, just to seal it off if you wanted.

 

[oldman2]

Ok Shy, I can do as you suggest and board out the central area getting them to duck & dive around the supports, but I just found another stumbling block to my plans.

I intended to fit a spacesaver stair to the loft in the space where the airing cupboard was as the landing is so small I dont have anywhere else suitable.
The stair would need a new hatch situated just about where the old heating tanks used to be and as you can see from the pic below the access to the rest of the loft from this area is more restricted than just a simple strut and collar.

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I wonder if the extra timbers were there because of the tanks weight or because the stairwell is below that area.

View media item 4705

 

[Shytalkz]

You can bin the two more or less uprights without a problem. they are not part of the original structure and are presumably additional bits for the water tanks.

 

[oldman2]

I was hoping you might say that Shy. That helps some, thanks.