This week: walls continue upwards, some major decisions and a trip to the Homebuilding & Renovating Show at the NEC!
Internal ceiling height. A problem arose this week stemming from the joists for the first floor. The span of our walls (approx 5.3m), ease of installation, the ability to make holes for services and lack of squeaking led us to select JJI joists. When their plan arrived this week however, they strongly recommended 300mm joists rather than the 245mm we had provisionally specified. Use of the 245mm ones was described as "marginal" - we had no choice. However, this meant a reduction in the ceiling height downstairs of the 55mm difference in joists. The required minimum ceiling height of 2.3m that used to be in the regs has been removed but it is still a sensible guide. We were already tight on that so we have had to add an extra course of bricks. This affected the stairs which now have to rise an extra brick. Stairs are tightly regulated with limits for the rise/going ratio, maximum angle of climb and head height clearance. With the hole for the stairs in the basement fixed we could not extend the stairs back from the wall because of the head height restriction. We were on the limit for increasing the rise so we have had to narrow the half-landing to allow the stairs to "go" further towards the wall. These things are never simple!
Under-floor heating design.Following last week's decision to use under-floor heating I have been doing some research. They generally require a maximum water temperature of 55C. This is below most conventional boilers output so the water you have spent money heating then has to be mixed with cold water! Understandably therefore, the manufactures design their systems to use the hottest water possible. If you use a heat pump (as I am) it can produce water at 55C but the lower the temperature required of it the more efficient it becomes. You therefore want an under-floor system designed to run as cool a possible, the opposite of
there normal designs. This is simply achieved by having more pipework. An extra expense at installation which will be rapidly recovered. This has other very significant advantages if you choose wooden floors - which I have. Lower temperature = less possible warping etc.
Homebuilding & Renovating Show - NEC. This time last year we did not have planning permission - this year we knew a lot of the exhibitors personally! With most of the house decisions made our list of exhibits to visit was greatly reduced. The most interesting from me (and most boring for my wife!) was the CTG (Convergence Technology Group) stand and their Kerpen HomeNet system. This is based on Cat7 cable and will make the house as "future proof" as possible. Investigation and negotiation continuing. Watch for developments!