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A_L last won the day on October 12 2017

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  1. Advice on DHW & heating please.

    With good air tightness, approaching PH levels 2-2.5kW of heat input should maintain temperature to very low levels (-10°C). The immersion will be the majority (not backup) heat source for six months at least for DHW. With total December PV production averaging perhaps 3.6kWh/day, DHW PV will be minimal.
  2. Trussed rafters, warm roof

    Tongue and grooved 18mm OSB should be reasonably airtight on its own, could always put silicone in the groove. Maybe this is a case for an airtight breather membrane outside the OSB so that you only have a problem if the air-tightness layer comes 'in-board' (at around the gutter level) Maybe a case for fully adhered membrane https://www.proctorgroup.com/air-barriers https://www.dorken.com/en/our-products/products/residential/delta-vent-sa.php
  3. Trussed rafters, warm roof

    This depends on your idea of a 'warm' roof. Mine is that there is a continuous layer of a substantial proportion of the total insulation above the trusses to reduce the temperature differential across the trusses and have them and everything below the insulation at near internal temperatures. Obviously this not the construction you want. If by a 'warm' roof you mean everything below the trusses at substantially the internal temperature then leaving a 50mm air gap on the topside of the insulation, running up to a ridge vent, or sometimes by fully filling the truss depth with insulation and using a suitable breather membrane below the roof covering. A VCL below the trusses would be necessary and I would put at least some insulation below the trusses to reduce thermal bridging through them.
  4. EPS beads in timber frame?

    @bissoejosh, do you have a BBA cert for pumped cellulose?
  5. EPS beads in timber frame?

    The only downside is likely to be a decrease in the 'decrement delay', or the ability to reduce/delay sun heat transferring through the structure and possibly causing overheating in summer. If the façade is of brick or dense block this would reduce/eliminate the risk. I am assuming that you have a cavity construction. If a lightweight 'solid' construction with render the risk would be increased. I have frequently encountered brick/cavity/timber frame walls incorrectly filled with eps beads (it invalidates the usual CIGA guarantee) but never experienced any technical failure so I would not expect any problems where you retain a void cavity.
  6. Snow, what snow?

    East side of Glasgow, 10" level snow over last 36 hrs, currently sunshine with intermittent snow flurries. Annoyed at Met Office for taking rainfall radar page off-line.
  7. Maintenance above a flat roof

    Long planks under the feet of the scaffold/ladders will be enough.
  8. Previous thread on similar topic - https://forum.buildhub.org.uk/topic/4553-corner-window-insulation/?tab=comments#comment-72824
  9. Motion sensors in hallway

    Beware the power consumption of motion sensors, could easily be 10W, that is a lot of LED light.
  10. Suspended Timber Floor Insulation

    If the PIR has a foil face put this uppermost. If practical put the supro underneath the PIR with adhesive or similar. Avoids multiple punctures from OSB fixings. PIR, especially foil faced has significant vapour resistance and acts as its own vapour check so would not bother with VCL if you do not already have it.
  11. hello and welcome, In regards the GSHP as a rule of thumb you will need 50m2 of land per kW of heat pump output. An alternative to insulating the whole floor is to insulate down the external walls to the top of the footings. Even without any underfloor insulation 100mm eps edge insulation to 0.67m could get you to about 0.6W/m2.K
  12. Epsom Salts

    Epsom salts are Magnesium Sulphate (MgSO4), are, as has already been said totally soluble in water at any practical concentration, inoffensive to your bath and easily removed by flushing with more fresh water.
  13. Corner window insulation

    You can use any insulation on the two external sides. Doesn't look easy to insulate on warm side, but if you want to, use, like Oranjeboom a VCL or a high vapour resistance insulation e.g. pir with foil/XPS/foamglas. Also prevent air circulation around corner post.
  14. Corner window insulation

    Can you post a cross section? The important consideration is to prevent condensation on the steel because of water vapour transferring through a low vapour resistance insulation (i.e. spacetherm/aerogel) to a cold surface
  15. Sheathing Board Options

    from :- http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15470 fourth comment from top