Attic Flooring

steps_3314

I'm thinking of flooring our attic. There is plenty of space available and a stira is already fitted.

I just dont know what type of floor boards to use. Chipboard or Plywood

I have heard chipboard is cheaper but may not be as strong as plywood.

I would use the attic mainly for storage but enough space is available for other things. I am thinking of putting the pc up there and an exercise machine for the missus.

What type of floorboard would support this and can i assume the joists will also support it.

Any advice appreciated?

Martron

i have seen packs in diy stores which is designed specifically for this. chipboard boards with a tongue and groove on them.

i would say light traffic would be alright but if you mean exercise machine i.e. treadmill i would not recomend that

Carlow52

steps_3314 wrote: »

can i assume the joists will also support it.

Any advice appreciated?

No you cannot.

The ceiling joists are un-lightly to be correctly sized for such loading.

steps_3314

Yeah i have heard the tounge and groove packs are handy to install.

Traffic would be light. But the exercise machine is one of those Ab King Pro's like below.

http://www.thanedirect.ie/products/abkingpro/abkingpro2.php

Martron

do a quick measure of the height and width of the joist and the spacing between them and we could give you a better answer.

ART6

Carlow52 wrote: »

No you cannot.

The ceiling joists are un-lightly to be correctly sized for such loading.

Carlow is right. You can floor over the joists and can walk about on the flooring, but in time the ceilings below will develop cracks as the joists will flex too much. OK for storage, but not for regular traffic and certainly not for exercise machines:eek:

Joey the lips

Hi folks as you seem to know a bit about attics I am hoping you can help me also no that the op seems to have the answer. I am thinking of flooring my attic simply for storage. Christmas decorations, kids toys, few tools etc. Nothing heavy as such. However I live in a timber frame house and am not use to the set up.

The joists are 22" apart.... Seems like a massive gap to me

4.5" x 1.5" Joists thickness.

Wires are surface mounted which is a complete pain in the arse,

This is what I am thinking.


I am thinking of buying lats of wood and tacking them to the joists this would allow the wires sit between the notches. Then i lay the chipboard flooring on top of the lats so the flooring is not pressing on the wires,

However 2 precautions i can see being required here.

1. The wires are very close to the surface

2. I would need to treat the lats and flooring with protim to prevent the possible introduction of woodworm. No its not present at the moment. Its just a precaution

Has anybody any knowledge on the size of the joists etc or my method of fixing the flooring.

ART6

Joey the lips wrote: »

Hi folks as you seem to know a bit about attics I am hoping you can help me also no that the op seems to have the answer. I am thinking of flooring my attic simply for storage. Christmas decorations, kids toys, few tools etc. Nothing heavy as such. However I live in a timber frame house and am not use to the set up.

The joists are 22" apart.... Seems like a massive gap to me

4.5" x 1.5" Joists thickness.

Wires are surface mounted which is a complete pain in the arse,

This is what I am thinking.


I am thinking of buying lats of wood and tacking them to the joists this would allow the wires sit between the notches. Then i lay the chipboard flooring on top of the lats so the flooring is not pressing on the wires,

However 2 precautions i can see being required here.

1. The wires are very close to the surface

2. I would need to treat the lats and flooring with protim to prevent the possible introduction of woodworm. No its not present at the moment. Its just a precaution

Has anybody any knowledge on the size of the joists etc or my method of fixing the flooring.

Ceiling joists are normally 1 1/2 by 4 1/2 inch timbers spaced 16 inches apart. Attic flooring chipboard is normally 16 inches by 48 inches with tongue and groove joints. With your joists so far apart the chipboard panels might not be strong enough without some extra supports, and unfortunately 16 and 48 inches are not divisable by 22 -- in other words the distance between joist centres over, say, three joists is 44 inches and not 48. You could probably get round that by cutting the chipboard back to 44 inches long and placing them at right angles to the ceiling joists, but then you would need to add cross joists to support their long edges. Clear as mud:)

The idea of fixing battens to the joists to clear cables is sound enough, but if you do that you should clearly mark the flooring where the cables run or someone in the future might drive a nail through them. Personally, when I floored our attic, I re-ran all the cables in bundles up and over the roof joists and used connector boxes to provide a diagnostic facility in the event of any future electrical issues.

Joey the lips

ART6 wrote: »

Ceiling joists are normally 1 1/2 by 4 1/2 inch timbers spaced 16 inches apart. Attic flooring chipboard is normally 16 inches by 48 inches with tongue and groove joints. With your joists so far apart the chipboard panels might not be strong enough without some extra supports, and unfortunately 16 and 48 inches are not divisable by 22 -- in other words the distance between joist centres over, say, three joists is 44 inches and not 48. You could probably get round that by cutting the chipboard back to 44 inches long and placing them at right angles to the ceiling joists, but then you would need to add cross joists to support their long edges. Clear as mud:)

The idea of fixing battens to the joists to clear cables is sound enough, but if you do that you should clearly mark the flooring where the cables run or someone in the future might drive a nail through them. Personally, when I floored our attic, I re-ran all the cables in bundles up and over the roof joists and used connector boxes to provide a diagnostic facility in the event of any future electrical issues.

So did you have to cut the attic cables to do this... Is this safe and a standard thing to do?

If my joist are slightly wider apart then would I be better using plywood?

ART6

Joey the lips wrote: »

So did you have to cut the attic cables to do this... Is this safe and a standard thing to do?

If my joist are slightly wider apart then would I be better using plywood?

When I floored my attic I took the opportunity to change my main switchboard from old fashioned ceramic fuses to MCBs and RCDs, so I was able to run new cables. I didn't need to cut any. I considered it worth doing for family safety reasons and for the opportunity to renew 25 year old wiring.

If you don't want to or can't go that far, then as I said, just make sure you mark where the cables go over joists under the flooring panels and make sure you don't trap any. Also, in that case i would suggest you fix the boards down with screws rather than nails as you will then be able to remove them easily if you need to get at cables at any time.

You could use ply instead of chipboard flooring, but given the spacing of your joists I would guess you would need to use something like 20 mm ply, and even then you will get a certain amount of flexing. That might not matter if you only want the space for storage, but 20 mm ply is very heavy in 8 x 4 sheets.

Joey the lips

ART6 wrote: »

When I floored my attic I took the opportunity to change my main switchboard from old fashioned ceramic fuses to MCBs and RCDs, so I was able to run new cables. I didn't need to cut any. I considered it worth doing for family safety reasons and for the opportunity to renew 25 year old wiring.

If you don't want to or can't go that far, then as I said, just make sure you mark where the cables go over joists under the flooring panels and make sure you don't trap any. Also, in that case i would suggest you fix the boards down with screws rather than nails as you will then be able to remove them easily if you need to get at cables at any time.

You could use ply instead of chipboard flooring, but given the spacing of your joists I would guess you would need to use something like 20 mm ply, and even then you will get a certain amount of flexing. That might not matter if you only want the space for storage, but 20 mm ply is very heavy in 8 x 4 sheets.

Yes it is very heavy but that is life. Thanks for the help. Will see weather I fancy cutting loads of packs or getting a delivery of ply, Knowing me it will be cutting loads of packs.

Thanks for the help again. as its only being used for storage. The packs save me having to be very neat though.

ART6

Joey the lips wrote: »

Yes it is very heavy but that is life. Thanks for the help. Will see weather I fancy cutting loads of packs or getting a delivery of ply, Knowing me it will be cutting loads of packs.

Thanks for the help again. as its only being used for storage. The packs save me having to be very neat though.

Good luck;)

Hell Toupee

If your attic door is wide enough - you can buy flooring grade chipboard in 8ft x 2ft tongue and groove. if will save a lot of waste and a lot of cutting. you could also add bridging pces between the joists at the centre of boards to eliminate the spring in the boards. With respect to the wiring, were you allow grooves for the wire bridge over the wire with strips of metal to reduce the risk of screws and/or nails being driven into the wires.
Hope this is of some help.

PeteHeat

Hi Joey,

Might be worth looking at fixing 2" x 2" laths at 16" centres to the ceiling joists with screws, no hammering so less chance of cracking the ceilings and mark where the wires run just make sure you avoid hitting them with the screws.

The T & G chipboard for attic floors is fairly strong when the joints are kept tight maybe even some wood glue in the grooves to give extra strength, fix the boards to the cross laths using screws making sure to break the joints.

Convert all of the above dimensions to metric, or the young staff at the counter won't know what you are saying

Flooring the attic is great use of space for storage, definitely not for regular traffic, office or mini gyms.

.

Stratocaster

steps_3314 wrote: »

I'm thinking of flooring our attic. There is plenty of space available and a stira is already fitted.

I just dont know what type of floor boards to use. Chipboard or Plywood

I have heard chipboard is cheaper but may not be as strong as plywood.

I would use the attic mainly for storage but enough space is available for other things. I am thinking of putting the pc up there and an exercise machine for the missus.

What type of floorboard would support this and can i assume the joists will also support it.

Any advice appreciated?

Ask your builders suppler for sterling board, its a chip board that comes in 8 x 4 sheets and most chippys recommend as best flooring for attics. I have it in my own attic. Great stuff easy to install, withstands a lot and no squeaks or creeks. Stay away from the green B&Q Woodies stuff it falls to pieces.

Joey the lips

PeteHeat wrote: »

Hi Joey,

Might be worth looking at fixing 2" x 2" laths at 16" centres to the ceiling joists with screws, no hammering so less chance of cracking the ceilings and mark where the wires run just make sure you avoid hitting them with the screws.

The T & G chipboard for attic floors is fairly strong when the joints are kept tight maybe even some wood glue in the grooves to give extra strength, fix the boards to the cross laths using screws making sure to break the joints.

Convert all of the above dimensions to metric, or the young staff at the counter won't know what you are saying

Flooring the attic is great use of space for storage, definitely not for regular traffic, office or mini gyms.

.

Catch your drift but dont understand this but. My joists are 22" apart!

Might be worth looking at fixing 2" x 2" laths at 16" centres to the ceiling joists with screws,

Can you just expalin again - Thanks

PeteHeat

Hi Joey,

I mean fixing the laths cross ways to the joists, the 2" x 2" laths will span the 22" between the joists you set the distance of the laths apart to suit the length of the boards you are using.

For extra strength try to stagger the joints of the laths on the joists as the joists are most likely 44mm wide which means you only get 22mm bearing where the laths are joined on the joists.

Also break / stagger the joints of the floor boards as this also gives the floor extra strength.

.

Joey the lips

PeteHeat wrote: »

Hi Joey,

I mean fixing the laths cross ways to the joists, the 2" x 2" laths will span the 22" between the joists you set the distance of the laths apart to suit the length of the boards you are using.

For extra strength try to stagger the joints of the laths on the joists as the joists are most likely 44mm wide which means you only get 22mm bearing where the laths are joined on the joists.

Also break / stagger the joints of the floor boards as this also gives the floor extra strength.

.

Got ya now. I thought the lads were a reference to the skinny laths I am putting down over the wire. Will do that. Also took the tip on board to stay away from the green stuff.

Thanks

william

Could anyone do me a big favour and sketch out how to floor an attic? The part I'm having difficulty understanding is how to put the floor on stilts/legs (which need to be high enough for 300mm insulation to run beneath). Many thanks. I couldn't picture what was described earlier in words.....:o William.

hbonbr

Has anyone any views on the thickness of chipboard required, 12 or 18 or 22 mm?