INSTALLITION AND ATTIC FLOORING

mick087

Im looking to do 2 things
1.Put down Attic installation
2. Put down some attic flooring to store stuff and move around.
My problem is I have a few pipes and some cables in the attic. Is it ok to cover all this with installation and leave the cables on top so just covering the pipes with the installation. The same when I put the flooring down I leave the cables on top of the flooring and cover the pipes with flooring marking were the pipes are.
How much installation should I use if im putting flooring on top, I want to be able to screw the boards on top of the rafters but if I put 2 layers of installation down I carnt see the rafters
What would be a good installation to use and whats the best boards to use
All tips and helpful remarks will be great thanks

antiskeptic

mick087 wrote: »

Im looking to do 2 things
1.Put down Attic installation
2. Put down some attic flooring to store stuff and move around.
My problem is I have a few pipes and some cables in the attic. Is it ok to cover all this with installation and leave the cables on top so just covering the pipes with the installation. The same when I put the flooring down I leave the cables on top of the flooring and cover the pipes with flooring marking were the pipes are.
How much installation should I use if im putting flooring on top, I want to be able to screw the boards on top of the rafters but if I put 2 layers of installation down I carnt see the rafters
What would be a good installation to use and whats the best boards to use
All tips and helpful remarks will be great thanks

There is no "correct" amount of insulation as such (although the building regs keep on demanding more and more and "correct" could be argued to be what current building regs demand). The "best" is to put in as much as you can afford - as good ceiling installation is a bit of a no-brainer when it comes to return-on-investment. You won't get close to modern standards with classic glass-fibre (you'd need 300mm/1 ft depth) without forgoing the flooring so you might consider a combination instead

- glass fibre/rockwool between the rafters
- sheets of solid foam insulation (50-80mm) laying on the rafters.
- wooden flooring laid on top of the insulation sheeting

This has the advantage of allowing you to work the rockwool around the electrical wiring between the rafters, whilst giving an uninterrupted layer of high performance insulation over the rockwool. You don't want wiring laying on the rafters (which will interfere with the solid sheets of insulation laying flat) so you'll have to cut notches out of the rafters to allow the cable to lie in the notch and below the surface of the rafter (holding the cable in the notch with a cable clip whilst you lay the solid insulation sheets on top of the rafters).

You'll have to work around pipework in similar fashion - removing sections of it temporarily perhaps, to ease access to the work area. Pipework is a little less flexible than electrical cable but so long as you don't leave holes in insulation it won't matter to much if things get a bit raggedy around pipes entries through your new floor.

A great decking wood is stuff called Smartply. It comes in sheet form of perhaps 4 x 1 foot - so it's easy to manage in an attic. It's also tongue&grooved so it doesn't matter if the joins between the boards don't land on a rafter - the tongue and groove gives sufficient strength to the joint without the need for rafter support directly underneath

Any builders supplier will have suitable solid foam insulation. Kingspan is probably the most common. Check if it comes in easy-for-attic sizes so that you can avoid having to cut it up. If cutting it up, make sure to cut in straight lines so that you can achieve good joins during assembly. Duct tape will assist in holding the pieces together whilst you assemble the solid insulation

Remember: safety at all costs. You're knocking around electrics and are going to be screwing sheeting down into areas in which electrical wires criss cross. Mark out where electrics run on a plan and work yourself gradually across the attic. Don't take chances if you're not sure what you're screwing into

*I'm assuming you've not got spotlights in the ceiling in question. If you have then ventilation issues arise.

paddy147

Make sure you do the attic floring right,otherwize your ceilings blow will crack all over the place.

slimjimmc

@antiskeptic,
surely you mean joists instead of rafters. Joists support ceilings and floors, rafters are sloped and support slates/tiles.

Also, if the roof is constructed from pre-fabricated trusses it is not recommended to notch the joists for wiring as this may introduce stress points which could weaken the structure. A better approach would be to lay battens along the joists and leave gaps between them for the wiring.

antiskeptic

slimjimmc wrote: »

@antiskeptic,
surely you mean joists instead of rafters. Joists support ceilings and floors, rafters are sloped and support slates/tiles.

When in Rome..

Our OP wrote:

...I want to be able to screw the boards on top of the rafters but if I put 2 layers of installation down I carnt see the rafters

The aim was communication - not correction. But point taken

Also, if the roof is constructed from pre-fabricated trusses it is not recommended to notch the joists for wiring as this may introduce stress points which could weaken the structure. A better approach would be to lay battens along the joists and leave gaps between them for the wiring.

I'd see this as a purist approach rather than a better approach. Laying a floor on the structure (and more insulation between the joists) - as well as piling an attic full of goods - could rightfully be said to 'weaken the structure' - but there is no suggestion that the structure cannot support such a thing.

So long as notch isn't taken to mean "large scale excavation" then we might agree there is no harm in progressing so. The engineering of the roof will easily support such activities.