Multi Gym in 2nd floor box room. Weight on floor?

[chrisforsterx]

Hi I'm putting a multi gym in my little box room. I've read as much as I can on this and other forums, as well as the Building regs.

6.4.9 Timber joists - NHBC Standards 2023

nhbc-standards.co.uk

I understand the basic 1.5Kn/m2.
But still wanted to be sure as after buying it, I've found the specs didn't include the correct weight, seems like they missed out the weight stack!

The multi gym is 240KG, I weigh 140Kg (Trying to lose 50KG). So the total is 380KG.
The footprint of the gym is a tripod form, with the rear taking about 170kg at centre and 1 rubber stopper feet either side approx 60cm, so a span/distribution of 120cm. The front centre leg seems to be approx 1m from the rear middle directly below the seat, so is taking the remaining 70KG and will take my 140KG.

The House is a 2007 new build and the room is 2m by 3.6m. The room's corner is 2 external walls and the gym will be at these walls.
I can't find which way the joists run, I can only guess width ways across the house as it's a tiny 2 bedroom. I can't get any other info other than it was built using pre 2008 building regs.

Using geometery the triangular formation still means the footprint is approx 1m2. but in real world terms it means it should span 4 joists any direction I place it due to the tripod form.

I have read other post about 700KG fish tanks that are only using 2-3 joists as they are long and thin and totalling 2m2. But it's been a bit scary to buy it and find the specs were 90KG out.

Hope someone can help,
Thanks in advance,
C.

 

[blup]

I had half a ton of plaster in the room for 3 months, nothing untoward has happened. Try spreading the weight over as many joists as possible maybe a sheet of osb

Blup

 

[chrisforsterx]

Hi thanks,
1. I was thinking of OSB as well.
2. Was your load in a new build 2007, Pre 2000 house were using thicker joists and pre 80's were much bigger?
3. I think it'll take me 18 months to lose the 50KG, at that point I was going to put it in a shed and just have lighter equipment, Do you recon it would be ok over a 2 year peiod.

 

[oldbutnotdead]

Your room is about 6 sq m so can theoretically take a load of 900kg evenly distributed.
As above, sitting it on a big sheet of 18 or 22 or 25mm of OSB or ply will help, or a couple of scaff planks.
What you have to be very aware of is any dynamic loads- presumably the weight stack is at the back? Is there any sort of shock absorbtion when the stack hits bottom? If not then it'll be really annoying for anyone in the room below (and next door) and could cause some damage if it happens frequently.
You can get some useful data from a laser measuring device (Aldi/Lidl have them every so often). Set it on the floor in the room below (roughly centre of the room above), mark where it is on the floor, mark the ceiling where the dot lands, record the result. Now put your gym in the boxroom, repeat. Now set the thing to continuous, get someone to note the readings while you use the gym a bit.

 

[chrisforsterx]

Your room is about 6 sq m so can theoretically take a load of 900kg evenly distributed.
As above, sitting it on a big sheet of 18 or 22 or 25mm of OSB or ply will help, or a couple of scaff planks.
What you have to be very aware of is any dynamic loads- presumably the weight stack is at the back? Is there any sort of shock absorbtion when the stack hits bottom? If not then it'll be really annoying for anyone in the room below (and next door) and could cause some damage if it happens frequently.
You can get some useful data from a laser measuring device (Aldi/Lidl have them every so often). Set it on the floor in the room below (roughly centre of the room above), mark where it is on the floor, mark the ceiling where the dot lands, record the result. Now put your gym in the boxroom, repeat. Now set the thing to continuous, get someone to note the readings while you use the gym a bit.

The weight stack is centre back, the tripod formation means it's feet hit about 1.2m apart. you can't really see in that picture but only the 3 feet touch the ground.
I'm gonna do that with the OSB, although it'll be about 4m2 (2m x 2m) or I can't close the door.
Some people on YouTube are saying that 2 layers of 9mm OSB rather than 1 layer 18mm. Don't know if that makes any difference.
I already had 2 sheets of 11mm, so 22mm in total. but don't know if it's still best to get a single 18mm.

Would defo apreciate any input you have about what you think is best (Also to anyone reading)

I'll try and get a laser measure. I don't have anyone who could just sit there, but I suppose I could record it on my phone.

And thanks for the reply.

 

[oldbutnotdead]

2 x 11 will do fine. Laser tape measure is always a handy thing to have, if you can measure the preload and postload figures it'll help put your mind at rest- on a span of 2 metres if there's 2mm or less difference then no worries.

 

[blup]

Hi thanks,
1. I was thinking of OSB as well.
2. Was your load in a new build 2007, Pre 2000 house were using thicker joists and pre 80's were much bigger?
3. I think it'll take me 18 months to lose the 50KG, at that point I was going to put it in a shed and just have lighter equipment, Do you recon it would be ok over a 2 year peiod.

i would think the activity would be as big a factor as the dead load. Place it as near to the wall as possible because the joists are able to take a much higher compressive load than in the middle.

Blup

 

[chrisforsterx]

2 x 11 will do fine. Laser tape measure is always a handy thing to have, if you can measure the preload and postload figures it'll help put your mind at rest- on a span of 2 metres if there's 2mm or less difference then no worries.

I was just looking at a laser measure. Unless I pay a lot I can get cheap ones which say "high-accuracy of ±2mm," Never had / used one so.

Does that mean it would only register a differance if it were over 2mm because the pics show it's display with 3 zeros after the decimal and in Meters, so that says it measures in nanometres. But that's just a pic and there's nothing in the descriptions for the cheap ones.

Thanks.

Edit: If all seems well and I measure once a day, then after a month, once a week. If it does measure in Nm and there is a shortening should I instantly dismantle or is there and expected tollerance / time to that 2mm cut off point.

 

[chrisforsterx]

i would think the activity would be as big a factor as the dead load. Place it as near to the wall as possible because the joists are able to take a much higher compressive load than in the middle.

Blup

Yes, It will be in the corner of 2 external walls. Although I do weight / resistance training in a controlled mannor. There's bound to be some weird flow as the weight transfers though the pulleys and my body weight against the force of lifting/ pulling. The weight will transfer force back and forth over the tripod legs.

 

[oldbutnotdead]

I was just looking at a laser measure. Unless I pay a lot I can get cheap ones which say "high-accuracy of ±2mm," Never had / used one so.

Does that mean it would only register a differance if it were over 2mm because the pics show it's display with 3 zeros after the decimal and in Meters, so that says it measures in nanometres. But that's just a pic and there's nothing in the descriptions for the cheap ones.

Thanks.

No, it means if you measured a Standard metre it could return a value between 998 and 1002 mm.
Can't remember if mine returns fractions of a millimetre but in my world that sort of precision is overkill.
I have used mine (Parkside) to measure beam deflection many times, it gives consistent repeatable results down to the millimetre.
An alternative is a long flexible tape measure fixed to the ceiling but that's a bit messier.

 

[chrisforsterx]

No, it means if you measured a Standard metre it could return a value between 998 and 1002 mm.
Can't remember if mine returns fractions of a millimetre but in my world that sort of precision is overkill.
I have used mine (Parkside) to measure beam deflection many times, it gives consistent repeatable results down to the millimetre.
An alternative is a long flexible tape measure fixed to the ceiling but that's a bit messier.

No probs, I got that wrong. Thank you.
So does that mean, let's say the ceiling is 1m and it reports 1.002m it would still react if the deflection was 1mm and report as 1.001m
Or
does it mean it could give random 2mm +/- every time. LOL, and I wouldn't know what panic to have!

 

[oldbutnotdead]

The first one.

 

[chrisforsterx]

Thanks, I'll give one of those a go.