Loft Boarding Questions

[zxzqz]

I want to start topping up the insulation and boarding the loft this w/e. From looking at these forums my current plan is as follows..

There are 3 main joists running along the house several feet apart that come up to 8in. I am planning to put 3x2 across these to bring up to 10in for insulation, then get some, say 18mm 1.8m long planks of some sort, so that each is supported at either end and in the middle by the 3x2.
Is this right?

Also should I be using planks or some sort of larger board, does this just come down to cost vs. ease of getting to loft etc.

Next what sort of screws should I be using? Do I drill a pilot hole in the 3 main joists for the 3x2, and then also in the 3x2 for the floor? How big and how deep are these? Do I drill clearance holes in the 3x2 and floor boards for the screws?

Sorry these are quite simple questions esp about pilot holes etc., not really done much like this before, but always learning. Just a bit worried about drilling into things I shouldnt.

 

[JohnD]

Not in order:

Yes you will find it much easier to put the screws in if you drill both clearance and pilot holes. Many professionals don't bother as they can do it quicker without, but they probably have stronger hands and more powerful rechargable tools than you, as well as a lot more practice.

Look for a countersunk steel posidrive screw that it 3 times longer than the thickness of the board. You should not have to countersink the hole as the screwhead will sink into chip as you tighten it. I prefer galvanised screws. Get a big box. You may find a decking screw that suits you.

18m flooring chipboard in 8' x 2' is quite a handy and cheap material IF you can manhandle it into the loft.

You will need the flooring supported at min 50cm intervals even if you are just using it for occasional storage. If you intend it to be a habitable room you had better contact your local council's building control.

Incidentally you will finfd it much more tolerable to work in the loft on a cloudy or rainy day than on a hot or sunny one.

 

[zxzqz]

Perfect, thanks.

Another thing. Just had a look and theres 4x2 running all over the loft, then just 3 of the 6x2 joists running over the 4x2, so coming up to 10in. This means I can board the area over the 3 joists fine but how can I board the area between the left joist and the left edge of the loft & between right joist and right side of loft, as only the 4x2 reaches the edges? Can I put 6x2 on the 4x2 to raise to 10in. or are these not supposed to take weight?

I think I will have a similar issue on one side of the loft where I think there are only the two outside joists and the centre one stops. This will prob be too far apart to do normally, so again can I put timber down on the 4x2 to extend the center joist, then 3x2 + board on top of that?

Hopefully can get on with it after this..

 

[JohnD]

A lot depends on whether you intend to use the loft as a habitable room, or just for storing the Christmas decorations.

Generally the thinner timbers are just intended for holding the ceilings up and the walls together, not for the weight of grand pianos and rowdy parties. If you counterbatten at right angles to the existing timbers, you will spread the weight which will help.

Wherever possible, place any new timbers so that the weight is transferred to the tops of the walls.

In my loft, the "edges" of the loft have little headroom, so I don't walk there, so I have not increased the depth of timbers.

If it is going to be a habitable room you will have to do it properly and consult your building control officer, who will know what you need to do and has probably seen hundreds of local houses just like yours.

 

[zxzqz]

Oh no, its just for light storage. The edge areas probably wont be walked on either for the same reason, but need to board it up so that theres something to put everything on once the insulation is down. At the moment all the junk just rests on the 4x2.

Does 'place any new timbers so that the weight is transferred to the tops of the walls' just mean keep the new 6x2 as close to the edge as possible?

Im looking (from wickes site) at something like, #12 4in screws for 3x2 into 6x2 joists giving 2in of screw in either bit of wood. Also #8 2in for the 18mm boards. Why do you recommend posidrive screws, does it make any difference?

Do the new 6x2 joists need fixing to the 4x2 underneath (if so how) or can it be left just attached to the other joists by the 3x2 & boards.

And finally does there have to be a gap between insualtion and boards, and also round the edges of the loft for air flow?

Thanks again.

 

[zxzqz]

Pls could anyone answer the above questions, esp attaching the 6x2 joists to the 4x2.. Thanks

 

[Static]

Patience, some of us arent logged on here 24hrs a day

Does 'place any new timbers so that the weight is transferred to the tops of the walls' just mean keep the new 6x2 as close to the edge as possible?

No, cross battern the new joists over the old at 90deg so the load is spread out over many existing ceiling joists.

Im looking (from wickes site) at something like, #12 4in screws for 3x2 into 6x2 joists giving 2in of screw in either bit of wood. Also #8 2in for the 18mm boards. Why do you recommend posidrive screws, does it make any difference?

Goto Screwfix for screws - cheaper. Posidrive are easyier to screw in.

Do the new 6x2 joists need fixing to the 4x2 underneath (if so how) or can it be left just attached to the other joists by the 3x2 & boards.

Screws?

And finally does there have to be a gap between insualtion and boards, and also round the edges of the loft for air flow?

Air gap should be left around the perimeter of the roof to let the cavity breath so taper the insulation away from the wall plate. I dont believe you need a gap between the boards and the insulation.

Also you might want to look into loft insulation grants with your local council

 

[zxzqz]

Hehe, yeah sorry, thanks for replying

Ok so this means like 8in. screws then? Dont remember anything that big at Wickes. On Screwfix I see Heco Topix T-star 200mm and external screws and thats about all that is long enough..

Is this what I want or am I missing something... Sorry if I'm being thick about this.

 

[Static]

Put them in at an angle (ie 45deg) not straight down