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24-11-2011, 16:43   #1
dilmal
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Partial Attic Conversion

Hi all,

First off, apologies - long post - hopefully the pictures will make it a bit less painful to read and easier to help with answering my questions!

I'd like to do a partial conversion on my attic - (ie: tongue & groove floorboards from Homebase and plasterboard) but I'm not sure the truss roof will support the extra weight.

I already floored the very centre area a few years back for easier storage but would like to be able to use the sides only for storage and the main space for maybe me, my acoustic guitar and my laptop, and do some recording (just for myself - wouldn't need studio quality/finish/sound proofing really). I didn't plan on putting insulation in behind the plasterboard (I read the roof needs to be left clear for ventilation and if the temp is too hot or cold, I just won't go up. It's usually tolerable though).

It would just be nice if I continued the floor out further and put up plasterboard sheets to cut down on dust and make it much brighter, more confortable and more useable. There will probably never be anyone up there other than me (at most, a couple of days a week for an hour or three) and I don't plan on storing heavy boxes or stomping around..

Below are some pics to give half an idea of what I'd like to do anyway.
It's about 16 foot between the two gable walls and the highest point of the truss is just over 9 foot.

The roof is a Double 'W' Truss. I would like to continue out the floor and put up plasterboard in the areas roughly marked in the following pics:

www.artexpanse.com/wp-content/uploads/attic/1.jpg
www.artexpanse.com/wp-content/uploads/attic/pbflb.jpg

www.artexpanse.com/wp-content/uploads/attic/pb1.jpg
(Actually, looking again now, I would probably put verticle laths from half way up the lower part down to the floor and plasterboard that, if it makes any difference)

www.artexpanse.com/wp-content/uploads/attic/2.jpg
(The pics were taken on my phone and the camera lens doesn't go very wide so I pieced the above together from 3 pics, obviously! The red line roughly indicates where I'd be putting up plasterboard)

My main concerns/questions are:

1. Will the truss roof support the weight of more floorboards and plasterboard sheets??

You're probably aware given the type of roof but to be clear, the attic 'floor' beams are held together in a good few places with the same joining plates as the rest of the truss beams:
www.artexpanse.com/wp-content/uploads/attic/joints.jpg

2. No doubt these plates won't take too much weight but how much??

3. Will the gap up the backs of the plasterboard and over the top be enough ventilation?

Another thing I'm unsure/weary about are the lengths of wood I've marked as "braces?" :-) in the pics below.
www.artexpanse.com/wp-content/uploads/attic/braces1.jpg
www.artexpanse.com/wp-content/uploads/attic/braces2.jpg
www.artexpanse.com/wp-content/uploads/attic/braces3.jpg
www.artexpanse.com/wp-content/uploads/attic/pbflb.jpg

These lengths of wood don't look very strong, were flung up (crooked, diagonally, not in line etc) with some nails and weren't cut properly. It looks like most of them were snapped over someone's leg!
I'm guessing these were nailed on (maybe temporarily?) just to keep the truss triangles/W's square and 400mm apart.

4. Can the 'braces' on the floor be safely taken away so I can put the floorboards down or would other support need to be put in place before removing them?

Needless to say, I'm a tad concerned that the roof is going to fall down with the weight of the floorboards and plasterboard. Are there any other concerns with doing this work?

Any pro or educated opinions/suggestions/help is much appreciated

Cheers
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24-11-2011, 22:56   #2
BryanF
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get a structural engineer to spec timber supports needed!!!

re plaster-boarding and insulation - you need to consider continuous ventilation of the rafters as I presume this felt is not breathable, then you need to consider adequate insulation and an air-tightness membrane before your get to plasterboard!!!
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25-11-2011, 11:03   #3
dilmal
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Thanks BryanF. I was afraid a structural engineer was going to be advised. I know you're right that it would really be the only way to know for sure, but it just seems like overkill for maybe 10 packs of t&g floorboard and a dozen sheets of plasterboard. (obviously not though when the roof comes collapsing down!!)

A structural engineer isn't an option because of cost so it will probably mean I can't do the job in that case.
I was just hoping someone here would say they've done the same job in a house with the same roof type and some carefully placed supports is all that's needed. Wishful thinking I spose.

Anyone here who HAS done the same type of job in a house with a 'Double W Truss' roof type, can you tell me what was required anyway? (A floating floor bracketed to the gable walls to support the weight of everything??)

The attic is ventilated all the way around the eaves and there is a roof tile vent. If plasterboard could go up, there would be ventilation up the back of the plasterboard and over the top to either side as I hadn't planned on adding insulation. That ventilation would be the whole way along the highest point of the roof so I don't think there would be much less ventilation than there is now. All of the rafters would still be getting good ventilation.
The felt under the roof tiles isn't breathable as far as I can tell. From a heat perspective, I'm not bothered about insulation. Is there any other reason for the insulation? (To stop the plasterboard absorbing moisture from the air?? Is this what an air-tightness membrane is for in relation to the plasterboard?)
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25-11-2011, 11:23   #4
BryanF
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Quote:
Originally Posted by dilmal View Post
structural engineer ... the roof comes collapsing down!!
the proposed without professional consultation is hazardous and dangerous, but the attempt to justify it, is just mental..
Quote:
I'm not bothered about insulation. Is there any other reason for the insulation?
you answered this:
Quote:
storage and the main space for maybe me, my acoustic guitar and my laptop, and do some recording (just for myself
my musical and electrical equipment is sensitive to cold and moisture..

personally I like to not have gloves on when I play the guitar!!
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27-11-2011, 13:59   #5
PeteHeat
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A truss roof is engineered to take the designed loads, unlike a cut roof there is very little room for forgiveness so do not attempt to add further loads or cut any of the supports out.

If converting an attic it is best to do it properly or leave it alone, as time moves on other uses tend to be found for the extra space like the occasional use guest bedroom, childs play room etc.

As a music room I expect you would have problems from neighbours or other people in the house as it would be like playing your electric guitar inside a drum, might be ok for a bit of background for your music but not great for the rest of the household.

.
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27-11-2011, 14:52   #6
gsxr1
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Quote:
Originally Posted by BryanF View Post
the proposed without professional consultation is hazardous and dangerous, but the attempt to justify it, is just mental..

you answered this:

my musical and electrical equipment is sensitive to cold and moisture..

personally I like to not have gloves on when I play the guitar!!
I left a Gibson Les Paul in my parents attic for 1 year. It was destroyed. clear paint came off. Might as well have been left out in the garden
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27-11-2011, 23:47   #7
whizbang
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You havent said you were going to cut any timbers out ?? If not:

there is nobody here going to tell you its safe to put down some planks to walk around on, but you all know everybody does it. Nobody's ever had their ceiling fall thro except by some extreme stupidity. just being here disproves that.

You cant take away the floor braces except if you drill and screw new floorboards down. but old school says you must screw down all flooring anyway.
Ideally you would put down some sheeting under boards to bring up finished height to the braces.
Put some ceiling rafters in and then shure you might as well use insulated plasterboard anyway.
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28-11-2011, 16:59   #8
dilmal
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Thanks lads.

My guitar is acoustic - some light, unplugged fingerstyle playing during the day or evening wouldn't be a problem for the neighbours or the rest of the household. I wouldn't have ever left it or the laptop up there, so cold or moisture aren't an issue. Well, no more so than playing in my sitting room for an hour or two with the window open.

BryanF, there's no attempt to 'justify' it...so no, it's not mental :-D The questions are perfectly plausable. If I knew for a fact that the roof collapsing was a possibility, I wouldn't be here asking. A structional engineer is naturally a pretty good guarantee but someone experienced could have easily come on saying my concerns were just paranoia, that truss roofs are designed with this in mind etc but I had absolutely no intention of taking silly risks regardless. I was talking/joking worst-case, highly unlikely scenario of the roof collapsing. It wouldn't happen because as I said earlier, the job won't be getting done if that is a possibility.

Roof collapsing aside, I didn't want to cause any unforseen long-term damage or issues from maybe major cracking in the ceiling below or a result of redirecting the airflow/moisture with the plasterboards, or that kinda thing.

Whizbang, cheers. No, I wasn't going to be cutting any of the timbers.
The existing floorboards (which is more than half of what I was proposing, floor-wise) are perfectly fine after the few years (no cracking or bowing of the ceiling below etc) so I might put down the few more boards and raise the height to go over the braces like you say. I think I'll be giving the plasterboard a miss though as advised.

I don't suppose there's a cheap, very lightweight, fire-resistant alternative that reacts well in an attic environment (varying temp and moisture) like hardboard? I know hardboard is going to absorb mositure like a sponge and wouldn't be fire-resistant (unless treated maybe) but it is very light - Lighter than some of the boxes that were up in the attic for storage. So not hardboard specifically, but anything along those lines just to section off the area a bit to cut down on dust and brighten up the place (painted with white fire-resistant paint?) or similar?

Cheers all. I appreciate the replies.
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01-12-2011, 15:24   #9
ronan45
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There are carpenters now doing I think what you might call "First Fix" Attic conversions.
Ie Steel RSJ Only
Window Only
Stairs Only Etc
Maybe you could get a qualified person to do the Important structural parts and you could do the plaster board and floors yourself?
Sub out the electrics and plumbing if neccesary?
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01-12-2011, 16:46   #10
dilmal
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That's an idea actually, thanks Ronan.
The money is limited of course but bit-by-bit with the steel RSJ(s) first etc could be a go-er in the future. I imagine a structural engineer would still be needed for that though - cost would add up very fast. Getting quotes is definitely a plan though.
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01-12-2011, 17:10   #11
ronan45
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Quote:
Originally Posted by dilmal View Post
That's an idea actually, thanks Ronan.
The money is limited of course but bit-by-bit with the steel RSJ(s) first etc could be a go-er in the future. I imagine a structural engineer would still be needed for that though - cost would add up very fast. Getting quotes is definitely a plan though.
Strutural Engineer about 200 Euro no? My friend got a strutural engineer out to do a survey and it cost her 140 included 5 page report
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29-01-2012, 16:39   #12
Svarryus
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Let us know

Hi Dilmal,

please post here if you done what you planned and maybe the costs?
planning to do same...

Thanks
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