Browse Forums Building Standards; Getting It Right! 1 May 13, 2014 9:39 pm We have a terrace above our living room. Our living room is 4950 mm wide by 9300 mm long. From the structural plans I can see the structural engineer said we should have 250 x 50 F11 joists. However, I'm not certain that's what we have as, from what I can see through a hole I put in the ceiling a while back, it looks like the joists may be less than 250 mm high, but have had other wood bolted to them. Attached are some pictures of what's been done. It looks like sistering, but the wood that has been bolted to the main joists is not the same size, so I'm uncertain as to whether we have a structural issue, or that it is an appropriate way to add strength, or if it's just the method the builder used to give some fall to the terrace above. Does anyone have any experience or suggestions? If I look at our living room, there is probably a bow of maybe 20 mm across the 4950 mm single span. Is this within the appropriate range for a 4950 mm single span? Other information that might be useful is that the previous owner has plaster boarded over existing plaster board to redo the living room ceiling. Basically, they nailed 25mm batons to the existing ceiling then added plasterboard. The question in my mind is, did they do this to cover up something? Also, we did have to replace the terrace and waterproofing above 2 years ago (though I'm not sure if this was just down to age of the existing waterproofing or if we have a bowing issue that's causing too much flex on the waterproof membrane). Appreciate any thoughts you have. Thanks Pics: Facing away from barge board, in to living room: http://postimg.org/image/43l1f7wd5/ http://postimg.org/image/e8ayknitf/ Facing barge board on outside of hours (Galvanized metal is above barge board) http://postimg.org/image/hrz3cafrz/ http://postimg.org/image/as6xz6sbt/ Re: Joists question 2May 14, 2014 8:40 am I'd say it is undersized. That size joist would be OK as a ceiling joist where all it is carrying is the plasterboard underneath but add 15 or 17mm compressed fibro on top then add a lot more weight with tiles and suddenly it is carrying much more than it was intended to. How are the tiles fixed to the waterproofing ? Sand/cement mortar or glue ? If sand and cement then that will add a lot more weight to it as well. By the way the second timber joist bolted to the side of the main one could also have been to make it easier for joining the AC sheets above. Two lots of plasterboard + battens hung underneath it isn't helping either Stewie Re: Joists question 3May 14, 2014 9:10 am It is a bad idea to plasterboard under existing ceilings as this doubles the weight of the ceiling. Domestic timber span tables are based on the timber carrying only one layer of ceiling. The bolted piece of timber may have been installed if the main timbers were bowed and this new piece of timber was needed to provide a flat surface for the cement sheets. Re: Joists question 4May 14, 2014 9:16 am Thanks Stewie, The tiles on top are fixed by glue, the grouting is sand cement. I guess the question is, given the structural engineer knew that it was a terrace above with compressed sheeting and tiles (it's in their drawings), why would they undersize? I guess the next step is to bring out a structural engineer to assess? Any ideas how much one would charge for an assessment? Thanks PS - missed detail above for the joists, they're spaced at 450mm Re: Joists question 5May 14, 2014 10:07 am Getting the engineer out is the best bet for sure. We can only tell so much from the photos. A bit more investigation on site from the engineer would give you a complete answer as to what is wrong and/or how to fix it given that some work has been done by the previous owner. An hour of his/her time even if it is $200 would be money well spent. Local engineers with minimal traveling time cost us around $175/hr as a guide. Stewie Hi All, about to commence a bathroom renovation and need some advice on subfloor works. Current subfloor is hardwood T&G floorboards on 90x45 joists, but intention is to… 0 5844 Thanks for all replies. I just noticed now the pictures I added to post right on top of page were wrong. I attached pictures showing "current" and my "suggested" floor… 9 14644 Houses have been framed on floor joists since settlement, chipboard flooring is only around for 50 years or so, so why would it not be satisfactory? However exercise skill… 3 16836 |