Converting loft space?

[BML]

I am past 70 years of age and I have a large loft area which my wife refuses to access because it make her claustrophobic so if I become unable to access the loft we will be unable to access any of the items up there. We are also running out of storage space downstairs and I am find it increasingly difficult to access the loft by loft ladder.

I therefore intend to convert the loft space to use for general storage and for working on my computer. I do not intent to claim that this will be habitable space and if I ever sell the bungalow it will be classed as accessible storage space.

The loft floor is covered with chip board and until I removed it the loft was stacked out with the belongings of my three sons which are not half the weight of the computer equipment I intend to install. The floor area supported by the ceiling joists is about 4M as a passage runs through the centre of the bungalow.

It is my intention to install a set of stairs to access the loft, to install two velux windows and insulate the area by placing some sort of rigid insulation about 100mm thick in-between the roof joists and round the space that I intend to use. The ceiling/loft joists are 80mmX50mm but as I said they have taken the weight of all the stuff from my sons but I know that they could do with being thicker.

I have two questions:

1. Would it help to strengthen the ceiling/loft joists if I were to screw another 80mmX50mm to the ceiling/loft joists or should I install additional 80mmX150 ceiling/loft joists?

2. When I place the 100mm rigid insulation between the roof joists should a gap be left between the insulation and the tiles?

 

[JerryM]

i am one for diy but know planning is key and this is not a simple job. suggest you read following from library "loft conversions, laurie williamson, isbn 1861263651" and roof construction and loft conversion, mindham, isbn 0632035951" and the posts in this forum on lofts.

there is also a very good website @

http://www.internode.co.uk/loft/index.htm

appreciate you don't want a full conversion and presume you will get quotes for the heavy stuff (stairs).

A1

80x50 or 80x100

it's the depth not width that gives the greater strength but new joist will be difficult given planned access is the new stairs. if it is just 1 person and a computer then i would give it a go. the trouble is i can see a gradual increase in load due to files, furniture, storage etc as it becomes used. only you can answer the question. totally risk free is the new joists (and why it's a building reg) against the risk replastering and fiiting new joist in the event that existing is no go. if i was going to trouble of 80x50 then go for the 80x100

A2 there must be an air gap to separate the outer "cold" roof from the inner "hot" roof