concerned about weight on walls and floors

[jul1313]

Hi,

I am in the middle of adding a ensuite to an existing bedroom. The house is an old weatherboard, however the room is definately an extension.

The walls, three of the walls are pine studs (90x35) and the forth is old hardwood (90 x38) , and the floor appears hardwood bearers and joist at 450 centres on concrete stumps.

So my concern is about the amount of weight being added to the structure.
We are adding
- 32m2 of tiling (floor and walls) at 25kg/m2 - total 800kg
- extra flooring (yellow tounge and tile underlay) - 200kg
- villaboard to 2.7m ceilings- no idea but couldn't be light ???
- plus vanity, glass etc

all this weight is in a room 2.7 x 1.8m , so it seems like alot of weight to add to a house, but I have never done this before so maybe it isn't.

Any one with any experiences with this kind of thing, could hopefully enlighten me?

Do I have any reason to be concerned about floors , walls failing, cracking, breaking falling down etc ????

Hopefully someone can reassure , because I am starting to get a little bit worried about something going drastically wrong.

[jatt]

I'm not a builder but this is how I would approach it.

do u have easy access to under the house? thinkin about the stump spacing, after all the room is realiant on them.

whilst u are there have a look at the general condition of bearers joists etc... if all looks well and the room isnt sinking on its foundations, you should a reasonable base to start from.

Because I'm a little predantic (think thats how you spell it) if possible I could sneak in a couple of stumps in the midspans of the bearers. If the ensuite is in the corner then I would look closely at adding extra if I thought I might be pushing the limits.


Good luck and course fotos, fotos

[jul1313]

When I look under there all looks fine ..... not sure if I can add extra stumps because of the existing plumbing from the rest of the house.

How can I tell if the room is sinking ???

[Bloss]

A start would be to simply do the sums to work out the added load m2 from those items you know you will be putting in. Without going into great detail AS1684 for light timber framing effectively uses ~40kg/m2 as a minimum for 'dead' loads (what you are adding) - and that includes all the loads being carried down to the sub-floor. That would be for regular 'light-weight' coverings such as carpet, vinyl etc. Adding heavier materials like tiles with an under-layer and so on would change the design specs needed. You are unlikely to cause any catastrophic changes, but if you exceed he design load by too much you can expect to see settling - and that will show as cracks and gaps in various places, doors not closing and so on.

When you do the sums come back and get some more advice - which will likely be more than just additional stumps, but could include doubling up of bearers (or extra rows) and maybe joists too. But estimates or guessing is not much use - get all the numbers, do the sums and come back.

[jul1313]

thanks bloss,

well what I have is
- 20.44 m2 of walls
- 4.86 m2 of floor

- TOTAL - 25.3 m2


added weight.

-tiles - 700 kg (50kg extra added for glue and grout)
-flooring (extra yellow tounge and underlay) - 200kg
- villaboard - 170 kg
- vanity - 90kg
- shower screen - 100kg (guess)

total -1260 KG

Now if I have down this right 1260kg/ 25.3 m2 is - 49.8 kg/m2.

So that means it is over what the AS1684 says (40kg/m2)

What do I need to do if anything? I may be wrong but if the villaboard is hung vertically does that increase the structural stability of the walls and maybe (hopefully) the load carrying capacity of the frame ?

Thanks again for your help

[Bloss]

Nope - the dead load is what is being carried by the sub-floor down to the ground - so what is bearing down on that 5m2 floor area alone. It is oversimplifying things a little, but the main added weight which will have any significant impact is what will sit directly on that floor area of roughly 4.9m2 (don't worry about more than 1 decimal) - so the 5m2 of floor tiles, the yellow tongue vanity and shower - that will be much less than the 1260kg (I assume you added in the wall stuff?) you used and although probably would take it over the 40kg/m2 is not likely to be a concern.

If you have underfloor access then takes some measurements at a few places that will allow you to check and recheck as you renovate. So for example bottom of bearers the top of the soil in a number of places - mark with a a texta or a thumb tack so you can measure at the same place each time. If you notice any movement you can then act to add some more timber or some steel - or other support as needed.

[jul1313]

oh ok....

so on the ~5m2 of floor there is,

125 kg of tiles
200 kg of flooring
100 kg (approx for toilet and shower screen)

vanity is wall hung

TOTAL - 425kg over 5m2

~65m2 / kg....... hmm seems alot worse.

So should that be of concern or should I just monitor it, as you mentioned ?

What about the load on the walls is there anything to look at with them ??

[Bloss]

Others might say otherwise, but I'd just monitor. Same with walls. So long as you will have post reno underfloor access to add support if needed it'll be fine. Little if any likelihood of catastrophic failure so if you do notice anything you'll be able to fix later. Most older homes in town residential areas were over-engineered (although there have always been 'jerry-built' houses Jerry built (http://www.phrases.org.uk/meanings/211600.html) ) so can easily manage large theoretical over loading which is based on current standards. Almost all buildings in the last 30 years or so are now constructed to statutory minimum standards - not a 'bad thing' and gives higher compliance to that minimum, but it also means that if you change any of the base parameters then you will need to re-look at the structure to account for those. A long way to say don't worry, just be aware - and using this forum already shows you are.

[jul1313]

cheers mate , I will still have access later so I guess that is what I'll do

[brianm627]

As long as your existing timber studs and joists are in good condition (not rotting) you wont have any problems with that weight restriction. No need to worry, go for it- and enjoy!!!