Attic Conversion

K09

Hi,

It is my mothers birthday shortly and we are planning to surprise her my doing up the house - painting and maybe attic conversion.

Our attic is a mess. It is just full of old junk and more junk is constantly put in there.
There is already a stairs up to the attic. I am planning on clearing out all the old junk and possibly putting down floor boards.

Now I have no experience in attic conversions. First of all I would just like to put down proper flooring. The attic floor at the moment is just the floor joists with the insulation in between the joists.
I do not know how strong the joists are but I imagine them to be pretty strong. The house is nearly 30 years old.

So what floor boarding should I use?? How much would it cost??

After that maybe put in plasterboards for the walls and possibly add in some shelving.

Any advice?? I would be very grateful for it.

Thanks.

AckwelFoley

Hello K09

This is a rather large undertaking.

The first thing i need to know is the size of the Joists. If the house id 30 years old im going to presume they are 4 x 2's, and in such case are too light if you are planning a habitable area in the attic, particularly if you have some large roo,s beneth.

The most common thing to do here is to put extra joisting up there beside the smaller ones. 9 x 2 is whats used now but you would get away with 6 x 2's . . this alone costs money. If you count the number of joists and the width of the house, i can give you an exact costing if you like

After that the next thing is the flooring. You can choose to place flooring boards directly on top of the new joists, but i d advise you get sheets of plywood 10mm or OSB 18mm, these sheets cover 32 sq foot each so divide the area of the attic by 32 and that will give the number of sheets you need, i can then give you the costing on that.

Next up is the walls. This is where it gets tricky The carpenter will need to remove and refit the collar ties (these are the lengths of timber at eye level running across the roof) the refit is needed to give you walking space, but extra timber needs to be added from the joists to the rafters to compensate for the collar ties been moved up.

From here i need more info.


You have the option of putting sa stud wall from the rafters to the joisting to "box off" a roomand excllude the inhabitable space of the attic.. this would be where the rafters are foo close to the joisting to be able to move around in. (thats the area behind the walls at the left and right of the picture below)



Do you want just a store area, or a finished area similar to the pic that you can have a bedroom in?

Windows need to be added, electrical word done etc, so if you can elaborate more on exactly what you want i can try to help.

Mellor

snyper wrote: »

Hello K09
The first thing i need to know is the size of the Joists. If the house id 30 years old im going to presume they are 4 x 2's, and in such case are too light if you are planning a habitable area in the attic, particularly if you have some large roo,s beneth.

Why would you make that assumption?
cut roofs were more common 30 years ago and have generally thicker sections than prefab.
Also, 30s ago all attics were sized to storage, today they are not.
My house is 30-40 years old and we have 200mm joists

The most common thing to do here is to put extra joisting up there beside the smaller ones. 9 x 2 is whats used now but you would get away with 6 x 2's . . this alone costs money. If you count the number of joists and the width of the house, i can give you an exact costing if you like

I think this is bad advice, you don't have any info on the OPs house. 9x 2 could be too big, correct or even too small.
The size of a joists depends on 3 factors (5 if you consider section dims), so they is a range of info that is required.

AckwelFoley

cut roofs were more common 30 years ago and have generally thicker sections than prefab.
Also, 30s ago all attics were sized to storage, today they are not.

I dont agree. I wasnt referring to truss roofs, and 4x2 joisting was used regularly in the 1970s, Either was she needs to support joisting with a min of 6 x 2. If you dont have the space you dont have the space, but im not going to advise anyone on my time to convert atticspace on 4x2 joisting.
I also disagree strongly that all attics were sized for storage in the 1970s.

Im not sure fully what type of construction anyone lives in that 9x2 joistng on an attic converstion is too small..

Mellor

snyper wrote: »

I dont agree. I wasnt referring to truss roofs, and 4x2 joisting was used regularly in the 1970s, Either was she needs to support joisting with a min of 6 x 2. If you dont have the space you dont have the space, but im not going to advise anyone on my time to convert atticspace on 4x2 joisting.

I never said you were refering to truss roofs, I was pointing out that they were less common that cut roofs 30 years ago.
You assumed that because the house is 30 years old it had 4x2s, this is a bad assumption imo.

Im not sure fully what type of construction anyone lives in that 9x2 joistng on an attic converstion is too small..

If you are not aware thats the problem isn't it. As I said the size of a joist required depends on three things. Depending on these 9 x 2 may or may not be the correct joist. Too big or too small.

9 x 2 is whats used now but you would get away with 6 x 2's . . this alone costs money.

Suggesting somebody could get away with 6x2 joists is not good advice ona public forum for a start, and also where you have no info on the house.

AckwelFoley

9 x 2 too big? Yet 6 x 2 is bad advice? :rolleyes:

Im only giving broad suggestions here, i dont have a plan of the job, but a suggestion on how its commonly done is not over shooting anything...




Look, i'll leave it to your good self from now on..

JamesM

I am in no way qualified to comment on this - so I'll just go ahead
I would think that K09 wants to spend a few hundred and get a bit of storage space in the attic - not 10,000 plus - which it could easily come to.
If the stairs are already there I would suggest using ordinary tongue and groove planking and screw it down. It is easy to lay and cut to shape, and also easier to get through the trapdoor than sheets of plywood.
Just an idea,
Jim.

Mellor

snyper wrote: »

9 x 2 too big? Yet 6 x 2 is bad advice? :rolleyes:

Im only giving broad suggestions here, i dont have a plan of the job, but a suggestion on how its commonly done is not over shooting anything...




Look, i'll leave it to your good self from now on..

Please don't mis-quote me or attempt to twist my words.
I never said 9x2 was too big, or 6x2 was too small.
I said they may be the wrong size. There are many more sizes of joist, and equal size doesn't not mean equal strength. Suggesting the OP "get away" with a wrong size is bad. Giving sizes that might be wrong is over-stepping im afraid, if they were wrong boards.ie would be liable. You post wasn't clear enough to a layperson that the correct size needs to be worked out.

muffler

snyper wrote: »

9 x 2 is whats used now but you would get away with 6 x 2's . . this alone costs money.

I have to say that I am also a bit surprised and disappointed at that comment. The OP give no indication of the span involved which for me is the first consideration. Based an an old "rule of thumb" a 6" x 2" would suffice for a 3 metre (10ft) span. But the OP should consult with a professional for this proposal - there are tables for calculating sizes of structural timber.

Making assumptions is a dangerous practice.