Floor joists

[No skills]

Hi all, quick and hopefully easy question for you. I need to replace and add in some extra floor joists upstairs, is C16 grade timber good enough or do I need C24 to meet building regs?

Ta!

 

[bosshogg]

First off you don't need to meet the building regs for repairs to your own house, I take it this is your own house?
You don't say why you need to replace some and add some extra joists, it may help if you do, also what span will they cover and what load will be applied to them etc. etc.
Graded timber is calculated to perform under predetermined conditions, not just in certain areas, such as floors, or roofs for instance, so spill the beans for a better response.
I'm not trying to be flippant, more proactive, but if you feel the need to ask, always go for the highest grade available, that will ensure you cover all the bases...bosshogg

 

[Lons]

First off you don't need to meet the building regs for repairs to your own house

In this case probably correct Bosshog but not as a general statement. At least not in England though I'm not sure about the Scottish regs.

Repairs certainly do come under the control of the local authority in a number of areas including certain demolitions, replacement windows, enlargement of openings, significant ventilation or drainage repairs, certain insulation upgrades and most (not all) electrical alterations and repairs.

Just don't want any newbies to misunderstand

cheers

Bob

 

[bosshogg]

You are quite right Bob, although just to clarify, I stated repairs, if as you state demolitions. replacement windows etc.etc. these can not be called repairs and some of those mentioned may even require Planning permission.
But back to the original post, we really require some further input, or as I stated - use the highest grade available to cover all eventualities...bosshogg

 

[No skills]

Well folks the replacement joists are for some that have rotted through water ingress and a long term pipe work leak - span is 3 meter give or take 10 cm. The additional joists are for a room conversion (not the same room as above), one bedroom being split into a small bedroom and small bathroom - need to double up on existing joists where the bath will be. Span is 3.5 meter give or take as above.

Any further assistance greatly recieved :ho2

 

[Dibs-h]

I'd just fit C24 and be done with it. The cost for C24 at my local suppliers is sold for the same price as C16.

The doubled up ones - I'd screw together or bolt up, so they act as one member.

HIH

Dibs

 

[mack9110000]

Just make sure whatever is supporting the existing joistwork will be able to take the extra weight.
mack

 

[No skills]

Joists are on load bearing brick walls either end, one side is solid 8" brickwork (old house, no cavity) other side is a single skin brick wall. Full brick width bearing on the single skin wall, havent actually lifted a board at the other wall yet but I'm assuming 4" bearing again.

The doubled up joists will be coach bolted together to act as one, if c24 is the way to go then thats what I'll use - I'd guessed at about £12-13 per length, will find out end of the month if I'm right :shock:

 

[bosshogg]

I agree go with C24, especially if there is no real price differential, you should also make sure they are treated. One other thing, the use of double sided timber connectors between joists where bolted, massively strengthens the pairing whilst still allowing for some movement. You can get these from most building suppliers, Screwfix and the like, in fact most outlets that sell joist ironmongery...bosshogg :ho2

 

[Lons]

I'd think about flooring out the bathroom bit with 3/4 wbp or marine ply while your at it. Screwed not nailed!

BTW Bosshog - you're right of course but local building control opinions vary and mine would certainly be interested in the repair or replacement of rotted joists of that span and would want to ensure they are properly sized, specced and treated as well as the bearing being sound. Any "new" bathroom would also come under scrutiny.

However I know many people who have done the work without approval or problem.

 

[bosshogg]

Gottcha Lons...bosshogg

 

[No skills]

I'm assuming the double sided connectors are the round washer type things with teeth either side?

Building control will be interested in the floor (bath support), bathroom electrics and waste plumbing, oh and ventilation/extraction especially in a room that initially will have no window.

I highly suspect BC were not involved with the last bathroom creation/relocation in this house, bath has no extra support (considering smallish joists imo), if you look behind the bath panel you will see a fair bit of missing floor and lots of electrical connections :evil:

Floorboards are being replaced in both of the 'new' rooms with some osb3 18mm, the bathroom floor is a touch more involved than the bedroom as I have to raise floor level 200mm (ish, one step) to get enough fall on the pipework for proper drainage, I imagine I'll coat the osb with an addition water proofing treatment before tiling.

Thanks for the help and info folks, anything else?

 

[bosshogg]

I'm assuming the double sided connectors are the round washer type things with teeth either side?

That's the ones, the gripping action joins the two joist timbers together is if one piece...bosshogg