Jump to content


  • Posts

  • Joined

  • Last visited

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

AndyFExtension's Achievements


Member (3/5)



  1. Following on from your comments as an alternative to just 120mm in between studs. what do you think to adding the below to improve comfort in summer and maintain a good u value: a - 25mm rock wool (100kg/m3) inboard of pir outside of vcl b) steico universal sarking board either instead of external osb sheathing or in addition to? both of them? I was thinking of adding 100mm EPS as external insulation could this also work in the above build up? many thanks
  2. Thanks for the comments. the office has performed well in the winter. The floor is suspended timber joists with 100mm PIR between. I have a small triple glazed window and I have 2g sliding doors. They are largely facing away from the sun. it is ultimately a small space (3m x 3m) so the P/A is 12/9
  3. Hi. I am looking to build a timber frame extension. as a stepping stone to that I built a garden office: 70mm PIR insulation in studs - cedar cladding 100mm PIR warm roof. In the warm weather the internal temperature is +1-2 degrees higher than outside even with a fan on - pretty unbearable today to work in. my concern is that I will be replicating the problem on a south facing extension (assuming 120mm PIR is used). My questions are: a) what did I do wrong with the garden office b) what should I have done differently and ensure I reflect in the extension my current thinking on b) is to mix up the insulation types e.g mineral wool and eps/PIR. many thanks
  4. Thanks for the comments. I spoke with the manufacturer of weatherkem boards and they confirmed that painting would be suitable for this application and provide a decent service life. on the PIR front, what are your views on having that external to the osb sheathing and sandwiched between two layers of breather membrane? are there issues for different thicknesses say either 25/50/100? I am aiming for a u value of max 0.18, although can go lower obviously
  5. My non scientific “real world” test is the price of 18mm osb at wickes. last year it was £25 it’s now £45.
  6. Here is the lumber futures price. Still way above where it was 15months ago but down from historical highs… also retail doesn’t perfectly match this commodity price either! so it doesn’t answer your question but I would imagine your price will be lagging the recent price reduction… stick or twist?!
  7. Hi. best practice is to aim for minimum of 1:40 in construction, to achieve 1:80 in reality. to work out what 1:80 needs to be take the run (length of the roof) and divide by 80. 2310/80 = 29mm
  8. Thanks I did consider that, however I first discounted it because I wouldn’t be able render it and then raise wall without cracking the render. is the cement particle board suitable for permanent exposure to the elements without covering (with render) but sealing the gaps?
  9. Thanks Peter. I have spoken to BCO and they are happy with the build up from a fire regs perspective (because of the cedral). Although on reflection I asked the question of fireline boards and they just said my proposed build up was fine - so need to confirm that! on the OSB point I wanted to have the osb and PB together to aid internal fixing in the future and also it provides a greater distance (68mm) between the inside and the VCL so less chance of puncturing the VCL unwittingly.
  10. Hi. I am self building a rear extension on 1950s semi. The walls are cavity brick block (no insulation). I will have to raise one wall to within 300mm of the neighbours extension so I am having to build the wall (or at least the external face) and raise it in one go. I have put together the following wall build up. Keen to get your opinions. constraints are: initial build access and future maintenance fire regs limit on value of thermal performance given the U values in the rest of the property. cost (to a certain extent) out to in: cedral weatherboard Counter battens breather membrane 25 or 50mm PIR Breather membrane 18mm osb 140mm frame therm vcl 38mm batten 18mm osb plasterboard (foil) Many thanks
  11. Hi. How did you get on with this? This is exactly what I am proposing to do, I am building an extension with a timber frame and one of the walls will be within 300mm of the neighbours wall.
  12. Hi, I am in the early planning stages of rear extension, it will be entirely self built I am keen to build the walls out of timber (6x2 stick frame), the proposed dimensions are 6000 L x 6500 W. I have built a couple of flat roofs before (e.g. for a garden office and shed), so i am looking at doing the same (4-5 degree pitch). to help manage the roof build up, i am considering using a RSJ/UC so i can span the joists from the beam at the mid point (the other thought is to use Glulam). If the wall is made up of a stick frame, is it possible to rest the steel on the frame (with suitable cripple studs), the weight on either end should be around 75-100kgs? i will be using a SE over time, but i am keen to resolve some of the key constraints as early as possible. Thanks in advanc
  • Create New...