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Robin, thank you for that. I am a structural engineer myself but not working in domestic sector. Have you got some rule of thumb when you are not worried about existing foundations. For loft conversions we always add the load onto the building but yet most of the jobs do not have to underpin the existing foundations. Obviously, we both know that the assessment of old foundation is a bit grey area as there are many houses standing on falling apart brick foundations and still doing great. One engineer told me that as long as the extra weight does not exceed 10% of existing load (some sort of rule of thumb), the inspector will not have any problems and we do not have to worry about underpinning or some sort of strengthening. How it looks from your experience, please? Thank you,
Robin, Sir! Could you make a video on how to properly stack a ceiling with exposed beams from the bellow? With all the vapor barriers etc.? I am worried about the dew points etc. which could destroy my timber down the line. It is cold loft at the moment but with an ambition to transfer it into a living space in the future.
Hey Robin. Really enjoy these videos. I've often wondered, is it possible to cut the end of the beams to match the pitch of the roof in your example? Would that have a significant effect on the capacity of the beam? Thanks. 👍
Yes, in this example you would cut the end of the beam to match the pitch of the roof. It would reduce the capacity of the beam at the bearing, but that is not usually the critical factor.
The potential lack of lateral restraint at the end of the beam could reduce the beams carrying capacity resulting in a lateral torsional type failure in bending, but more realistically a localised failure close to the support is possible if you take out too much so there are limits and ways of doing this safely. As Robin infers a shear failure in the beam at the support is very unlikely to govern the design and so if the beam is a relatively long beam, agree you can cut it down in most cases, but best to get it checked by a structural engineer and also get it detailed properly especially if it working hard to fit into a confined space. The most robust way would be cut it to suit, to weld back a raking top flange to retain a similar section, and fix with two anchors to the centre of the load bearing wall, suited to the particular wall construction. Note the compressive strength of the timber top plate "packer" means it can often still take a significant load before crushing, so this could be ok to for lightly loaded beams without removing, just fix right through to the wall below. Again depending on how much the beam is carrying, but didn't seem like a lot to me in this example, maybe 20 kN over at least 10000 mm2 so 2MPa end bearing on a 4" plate, that should be OK. If its taking more than 2T at each end then best to remove the plate as in the video. Is this in the UK, just wondering about earthquakes.
What would you do if your celling joist were not resting on top of the walls as the ceiling height was higher than the top of the walls. So in the corner of the rooms there is plaster board attached to rafters creating an angled bit of ceiling
Robin, Great video. Could you not do this with wooden I beam joists side by side to the existing rafters. With Simpson I loft brackets tor the slope of the roof? Be great to have a video on this method.
@@RobindeJongh I am keen to understand the correct procedure for applying the correct materials in the right sequence to be compliant with building regs for a garage conversion. Do you have any advice on finding these out? Thanks in advance
Thank you this is very helpful. I am looking at a specific scenario for my property where the ceiling height is around 2m-2.2m and I am looking to do a dormer loft conversion. I wanted more headroom if possible. What are all the ways we can gain head height? Also is it possible to sink the steel beams gable to gable into the existing ceiling joists which will be perpendicular to the steel beam. I would be very grateful if you could reply to me and a video if possible since I am looking to start the work. Thanks.
Hi Asadullah. 2.2m is very low for a loft conversion. The best option would probably be a full dormer, since that has a flat roof at approx ridge height. Yes there are ways of sinking steels into the floor.
@@RobindeJongh Thanks for the reply, really appreciated. I am looking to do a dormer extension. I understand that 2.2m is very low for ceiling height. What are the best ways to gain head height? Other than raising the ridge itself since I wouldn't get permission for this. How would I sink the steel into the floor while maintaining structural integrity?
Hi im in Sydney Australia Liveable height is 2.2m so you have to consider lowering the floor by 300mm and ceiling height of that below floor is 3000mm so you'll end up with 2.7m below and 2.4 in lift here we call it attic conversion i hope it goes well with you thkx
Hi Lester. Yes a steel along the party wall can work to avoid party wall dispute. Regarding concrete lintels, the structural engineer would check the load and select the right lintel, and if necessary us a steel beam.
Could not the existing ceiling joists be piggy backed by gluing and screwing a timber on top of them .e.g. if the existing size was 4x2 a 6x2 could be piggy backed making it a 10x2 laminated beam ?
Hi Voda. This would still not span the 7 or 8m or so that you would need. Timber generally only spans 5m or so. And also it would leave your roof totally unsupported.
@@RobindeJongh Would it do 4.2 m ,if the apex was cross braced say with 1.2m lengths .Then sister every third joist and put a vertical wall either side meeting the rafters half way between the eaves and the cross brace.The pitch of the roof is 60 degrees.
