Notching attic floor joists

Roxee · 23-02-2015 12:42pm #1

Hi, looking for some opinions from experienced folk.

Getting attic floored, just for storage. Some pipes and wires run over joists, so option is either to raise floor and avoid them, or cut into joists where necessary and bury them (not doing it myself, I intend to have someone do it who knows what they're doing!)

Raising the floor adds to expense so I'm trying to see if there's any way notching joists is acceptable? Each person I've had quote me says a different thing. The joists are close (11 inches) and the partition walls below are solid, so one guy says there's no issue structurally, he's doing it 10 years etc.

Presumably the area of the joist being notched matters (further away from centre the better etc), and only cutting minimal depth needed etc

My question is... is it ever possible to notch joists safely, in theory, or am I gambling with my house structure?

Thanks!

Carpenter · 23-02-2015 1:42pm

What size are they ???? or is a truss roof

Flood · 23-02-2015 2:00pm

Cross batten the joists, wont add too much to the job, notching joists is a disaster on idea that should be left back in 1970.

Roxee · 23-02-2015 2:30pm

Flood wrote: »

Cross batten the joists, wont add too much to the job, notching joists is a disaster on idea that should be left back in 1970.

Hah, that's kinda what I needed to hear, thank you! I just couldn't work out if I was being too careful or not careful enough, due to different guys swearing blind on different things. Have since spoken to someone else I trust so definitely going to spend the extra and raise it. Good stuff, thanks again!

jack of all · 23-02-2015 3:09pm

As already suggested crossbattening is the best solution- it won't have any structural impact,it allows easier access to wiring/ piping in the future and it is reversible. Notching joists is best avoided and even when it is done it should only be done near the bearing points. The additional batten depth allows a little bit of extra insulation depth, if possible you should run some insulation over the existing joists (to reduce thermal bridging through these substantial timbers).

Roxee · 23-02-2015 3:47pm

Thanks a mil for the advice, really appreciate it!

Boiled-egg · 25-02-2015 5:55pm

Agreed, cross batten. It won't add much in cost and is far better.

Calahonda52 · 25-02-2015 8:06pm

Agree with X battens,
I use 2 by 2 rough, and build it up to suit
just remember that the elec cables need to be kept clear of any insulation, especially the power ones

Bruthal · 25-02-2015 8:11pm

Take care to avoid pinching and/or nailing cables.

It is easy to catch one without noticing.

Avoid heavy hammering to reduce risk of damaging plaster on ceiling below. Id drill and screw with screw gun if doing it.

Remind Me Tomorrow · 25-02-2015 8:59pm

Recently floored my attic. I used insulated loft boards and notched the insulation, rather than the joists.

Notching attic floor joists

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