Garage conversion raising floor height

[Al@n]

I'm in the process of carrying out a garage conversion and would like your thoughts in terms of what would be the best option to raise the height of the garage floor to the rest of the house. The difference is 610mm!

Would a suspended timber floor be the best option?

 

[securespark]

I would say so.
But are there any drains that would be concealed?

 

[conny]

Make sure you install air bricks to ventilation under the suspended floor.

 

[Al@n]

Make sure you install air bricks to ventilation under the suspended floor.

Sure will do, what timber joists would you recommend? Are they treated? Just concerned about damp etc
The size of the area is 4.97 x 3.70m

 

[^woody^]

Does this involve a building regulations application?

 

[Al@n]

Does this involve a building regulations application?

Yep it will be all done via BC

 

[^woody^]

Then building control will be expecting a ventilated void, and treated timber is only a requirement depending on site conditions and location within the UK, but the cost difference is negligible.

 

[Al@n]

Then building control will be expecting a ventilated void, and treated timber is only a requirement depending on site conditions and location within the UK, but the cost difference is negligible.

As the difference in cost is minor, I'll go with the treated timber option, what size joists would you recommend?

610mm is the height to the rest of the house, so I'll be deducting 22mm for the chipboard flooring and 8 to 12mm for the final flooring finish, which leaves me with 580mm, I believe there also needs to be a gap of 100 to 150mm? Between the concrete floor and joists

 

[Leofric]

If you are spanning 3.7m use tantalised softwood joists at 400mm centres with herringbone strutting

(galvanised metal straps )​

at mid span.
That will leave you more than enough between the concrete and underside of joists. As a matter of interest, does that mean your finished ground floor level is about 610mm above external ground level

 

[Al@n]

If you are spanning 3.7m use tantalised softwood joists at 400mm centres with herringbone strutting

(galvanised metal straps )​

at mid span.
That will leave you more than enough between the concrete and underside of joists. As a matter of interest, does that mean your finished ground floor level is about 610mm above external ground level

What would the benefit of using herringbone strutting?

What size joists size would you recommend I go for?

Is tantalised treated wood? I don't want the wood to be affected by damp/moisture long term.

The drop from the lounge into the garage is 610mm so i need to make up the height of 610mm within the garage to get it level so I have no step down

 

[Notch7]

What would the benefit of using herringbone strutting?

What size joists size would you recommend I go for?

Is tantalised treated wood? I don't want the wood to be affected by damp/moisture long term.

The drop from the lounge into the garage is 610mm so i need to make up the height of 610mm within the garage to get it level so I have no step down

7" x 2" probably.

you could screw a wall plate all round, then fit joist hangers the stick your joists in.

You could pin 38 x 19 batten to either side of joists and drop in insulation.

herringbone strutting increases stiffness -although for 7 x 2 you could just use solid noggins

 

[Al@n]

7" x 2" probably.

you could screw a wall plate all round, then fit joist hangers the stick your joists in.

You could pin 38 x 19 batten to either side of joists and drop in insulation.

herringbone strutting increases stiffness -although for 7 x 2 you could just use solid noggins

Excellent thanks, so is tanalised timber the same as kiln dried, and treated timber or are they 3 different types? or perhaps more

 

[Notch7]

Excellent thanks, so is tanalised timber the same as kiln dried, and treated timber or are they 3 different types? or perhaps more

You need stress graded timber either C16 or C24 and it needs to be treated. Lots of merchants just stock treated these days.

Yes its all kiln dried, but be aware treated timber is often stored at merchants outside so if bought during a rainy period it could be sopping wet (why do they do that Grr).

Its sold in 0.3m increments, but merchants will only have a few different length packs so have ring around.

Quality varies, so ringing round to save a few pence prob not worth it, if you have time pop in see what theyve got.

Buy hangers to suit the timber 7 x 2 is prob 170 x 45 -hangers come in 45, 47, 50

 

[Al@n]

You need stress graded timber either C16 or C24 and it needs to be treated. Lots of merchants just stock treated these days.

Yes its all kiln dried, but be aware treated timber is often stored at merchants outside so if bought during a rainy period it could be sopping wet (why do they do that Grr).

Its sold in 0.3m increments, but merchants will only have a few different length packs so have ring around.

Quality varies, so ringing round to save a few pence prob not worth it, if you have time pop in see what theyve got.

Buy hangers to suit the timber 7 x 2 is prob 170 x 45 -hangers come in 45, 47, 50

Thanks for the useful info, how can i calculate how much I'll need based on the length and width of the garage?
Is the preferred method two screw or nail them?
Securing the wall plate to the wall, what would you recommend?

 

[Leofric]

What size joists size would you recommend I go for?

Sorry, I meant to say 'If you are spanning 3.7m use 200 x 50mm tanalised softwood joists at 400mm centres '.
170 x 45 might be ok, Notch 7 will have to confirm that, I know 200 x 50mm at 400 crs

will span up to 4m ok.​

The drop from the lounge into the garage is 610mm so i need to make up the height of 610mm within the garage to get it level so I have no step down

yes ,I understand that but garage floors are usually near ground level which implies your finished ground floor level is about 610mm above ground level - is that the case ?

You could pin 38 x 19 batten to either side of joists and drop in insulation.

yes you will need insulation, but what are you converting the garage to ? Building Control will need to approve the insulation specification as well as other things.