Suspended Timber Floor in Garage Conversion

[Pepperpigsdad]

Please help. Never done a timber floor so all help appreciated.

The garage is 254cm wide.

I will use 45x125mm c24 timber in 2.4m lengths. I will mount ledger boards to the two longest opposing walls. If I mount just one ledger board to both walls I will have a span of 245cm. A 245cm gap will waste a lot of timber because timber is sold in 240cm lengths.

So I propose to mount one ledger board to one side and two ledger boards on the other side. This will result in a span of 240cm. Is it OK to mount two ledger boards together on one wall?

Also do ledger boards need to be set away from the wall? I read maybe this needs to be done to prevent damp.

Also how do I know what is the best way to fix the ledger boards to the brick wall? Do I need m12 rawlbolts? Do these need a resin to be set in the wall securely?

Any tips to get the ledger board perfectly level?

Thank you so much for any advice

 

[Pepperpigsdad]

Just thought of another question.

How far apart should the bolts in the ledger board be?

Also when drilling multiple bolts into the wall they will be surely uneven by at least a few mill. How do people make these ledger boards perfectly level?

 

[Notch7]

You could buy 5.1m or 5.4m boards and cut in half

bolt I’d guess 600mm spacing would be fine.

why do you need a suspended floor -usually garage floor is only 150mm below house, so joists laid on spacers is fine, some people do floating floor over insulation

 

[oldbutnotdead]

First thing, timber merchants supply 2.4, 2.7,3, 3.3 etc etc up to 4.8 usually. You'll need offcuts for noggins anyway so get the 3s.
Second thing, if you're worried about damp either fix a bit of dpc to the back of the boards or use dwarf walls and don't bother with ledger boards at all.
Fixings- usual trick is set it level, fix to wall with 2 or 3 of those concrete screws (or drill and plug) then mark where your joist hangars are going and use expanding bolts every 600mm or so placed where they're not fouling the hangars and they're not in a mortar course. You drill M10 or M12 hole in timber and straight through into masonry, stuff the bolt in, rattle it up with impact driver, done.

 

[^woody^]

Your doubling up on one side idea is OK. Consider fitting a few bits of timber directly below the outer timber down to the floor below every second joist to act as struts to remove the rotation force on the wall fixings. You can use screws to fit the 2nd timber (5mm or 6mm), but every 400 or so and stagger them - first one third depth down, then next one third up and so on. Recess the wall fixing bolt head into the second timber.

m10 will be fine every 500-600mm. You don't need resin

Its best to do what you can at waist or bench height before messing about on the floor.

Cut the ledgers to length, mark the hangers, offer to the wall and mark the bolt locations - to avoid joints and avoid hanger locations, drill the bolt holes in the timber, fit the hangers, offer the board to the wall, and use temporary supports below to get the correct level, drill one fixing hole (nearest to the centre) and fix, adjust the level as necessary, dill and fix the two ends, then the intermediate.

You might want a string line from end to end to make sure you are fixing straight. Or a line laser.

You should have a DPM across the floor and up the walls.

 

[Pepperpigsdad]

You could buy 5.1m or 5.4m boards and cut in half

bolt I’d guess 600mm spacing would be fine.

why do you need a suspended floor -usually garage floor is only 150mm below house, so joists laid on spacers is fine, some people do floating floor over insulation

both my local timber yards only sell in max 4.8m

garage floor has a 23cm drop. I spoke to building control who suggest a suspended timber floor. They said floating floor over 150mm of insulation might be spongy.

 

[Pepperpigsdad]

First thing, timber merchants supply 2.4, 2.7,3, 3.3 etc etc up to 4.8 usually. You'll need offcuts for noggins anyway so get the 3s.
Second thing, if you're worried about damp either fix a bit of dpc to the back of the boards or use dwarf walls and don't bother with ledger boards at all.
Fixings- usual trick is set it level, fix to wall with 2 or 3 of those concrete screws (or drill and plug) then mark where your joist hangars are going and use expanding bolts every 600mm or so placed where they're not fouling the hangars and they're not in a mortar course. You drill M10 or M12 hole in timber and straight through into masonry, stuff the bolt in, rattle it up with impact driver, done.

Genius, thanks for the advice I will go for one ledger board per wall then use 3m lengths which will allow the correct joist for the 245 span plus noggins at 50cm spacing.

I am not worried about damp. But to be safe I might fix some DPC to the back of the boards. Doing dwarf walls is a bit much for me, dont want to go down that road.

good tips about joists and mortar course impacting bolt position. thanks

 

[Pepperpigsdad]

I am looking at joist hangers and a bit confused.

My timber is 45 x 125mm. Ledger boards are timber so I am fixing timber to timber.
I want my joists to be the same level as the ledger board.

So am I right in thinking I cannot use the hangars that bend over the top of the joist because that will make my OSB board uneven when I come to screw it down?

The only ones that seem suitable are these multi truss hangars
https://www.screwfix.com/p/sabrefix...ck/82567#product_additional_details_container
Are these the right ones I need to use? They seem to be the only ones that accomodate my 125mm length board.

All other joist hangers are mini which support up to 100mm length or standard leg which support 150mm+

Why are the ones suitable for my wood size called multi truss? I am only fixing one joist to one ledger baord. Also how come mine are double the price of all other joist hangers? Am I definately looking at the right ones. I have looked in BQ, Wickes, Screwfix and Toolstation and it seems no normal joist hangars suit 125mm length wood.

 

[Pepperpigsdad]

Ignore that last post about joist hangars

I've gone to screwfix and looked at the standard jiffy hangars 10 for 10quid with standard legs. The min joist they accommodate is 120mm which should work for me. I will fold the leg over the top of the joist and cut off the excess.

Also the metal is only 1mm thin so won't make the osb uneven.

 

[Deleted member 174758]

So am I right in thinking I cannot use the hangars that bend over the top of the joist because that will make my OSB board uneven when I come to screw it down?

It is only a couple of millimetres, so TBH it's really neither here nor there. If you are that concerned about it you could always chop out some 3 to 4mm deep housings across the tops of your ledgers and wrap the joist hangers over them.

I've gone to screwfix and looked at the standard jiffy hangars 10 for 10quid with standard legs. The min joist they accommodate is 120mm which should work for me. I will fold the leg over the top of the joist and cut off the excess.

I always been told that you never cut joist hangers simply because the manufacturer hasn't specified that in his design. Some BCOs will also pull you up on that if they see it. Similarly you generally need to use sherardised twist nails and every hole should have a nail in it (and before some pedant points it out some manmufacvturers do permit screws in some of their joist hangers, but those are very specidic hangers used with specified screws from the same manufacturer - so not really a mix and match solution)