Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)


Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!

powered by Surfing Waves

Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.

    • CommentAuthornkmanglam
    • CommentTimeSep 25th 2007 edited
    Hello All,

    I have joined this forum today. I have been reading postings oin this forum for quite sometime now and finally i got time to share my house renovation problem.

    I have lived in this detached 4 bedroom dormer house (buit in 1968) since october 2005. I moved in this house in 2005 winter, it was very cold even when we had central heating on for 24 hours, which increased my gas bill to almost £200 a month. This house didn;t have cavity wall insulation, i got this done in january 2006. Soon after that i got central heating quote and got whole of central heating replaced (indluing all old radiators). After getting new central heating installed, i thought my gas bill would reduce drastically as i have condesning combi Worcester Greenstar Highflow 440 instaled now. But contrary to my imagination my monthly gas bill is still close to £150 a month, but i must admit this house has become habitable now.

    I was reading on internet that if i have undefloor heating done it will reduce my gas bill further as ambient temperature for UFH is only 19 degree compared to 21 degree for convetor heating. I am told my my ocal building inspector that i will have to use 50 mm underfloor celotex insulation because i have suspended timber floor. I have decided to exceed this isulation requirmenet and put 100 MM celotex insulation board. I have been told that wet under flor pipes should be cliped on celotex insulation between timber joists. And to increase thermal mass i should use 25 MM sand and cement screed to cover UFH pipes which will keep the floor warm for longer duration.

    My question relating to Under floor heating is that does it really reduces energy requirements ? will 19 degree will be ambient temperature if i have UFH? Do i ned a joiner or a builder to put these insulation board and UFH pipes ?

    My Next worry is that i on first floor carpet floor gets really cold because and in windy days carpet gets lifted upto 1/2 inch due to wind coming between ground floor roof and first floor flooring. i had roof repairer coming and they claimed that they fixed the problem by changing felt. BUt i can still feel the cold air coming under my first floor carpet and whole carpet is very cold. though OVERALL TEMPRATURE goes tro around 21 to 22 edgre when we have our central heating on.

    Both side of my house has dormer roof which is below window. I have feeling that both sides dormer roof need repairing. Do i need this dormer roof repaired from inside or outside?

    Both side of dormer has not got brick wall but rather it has plaster board which is very very cold in winter.

    DO i need to get both side of dormer roof changed ? Behind this dormer roof there is only single brick wall.

    What is the best method to achieve below 1 U value for my house?

    Do i need to contact a structural engineer or an insulation consultant ?

    Because one side of roof felting was repaired by a local roofing company and charged me £700 and said he has insulated external wall so to prevent any wind coming under my first floor. This company gave me 10 years gurantee and i rang them to complaint that I still have wind coming through my floor and i was told that this
    roofing company is no longer in business now.

    Is it norma to leave ventilation for joists on the first floor between ground floor roof and first-floor floor?

    I have my roof well insulated with fibre glass. Do i need to insulate inside of roof frame with celotex board?

    My house is on seaside and its very windy in winter.

    I am quite reluctant to contact local builder before i really know what needs doing in my house.

    I will be grateful for your help and advice.

    Thanking You al in advance.


    • CommentAuthorchuckey
    • CommentTimeSep 25th 2007
    Your very first job is to block up/ repair or otherwise fix the air ingress into first floor, floor void. Your downstairs ceiling is at out door temperature as well as the bedroom floors. This is a massive heat loss!!!!
    Any form of central heating replaces heat your house has lost to the outside. They have different charecteristics BUT the total energy use is the same. Don't fiddle about with UFH, it will not save you any money (unless you go to ground source heat pump technology)
    Insulating under your downstairs floor will help a bit -3% of your bill?
    Your plan of action is :-
    1. Fix air leakage in first floor void.
    2. Fix dormer window insulation.
    3. Increase loft insulation to 8".
    4. Insulate under ground floor.
    99. Fit UFH (unless GSHP)
    I'll agree with all of that.
    • CommentTimeSep 25th 2007
    GSHP is unlikely ever to be cheaper or greener than gas but I agree that UFH is not a good idea.

    It doesnt matter how much insulation you install if your house is draughty then it will be a waste of time.

    You need to draught proof the house , starting with your floor void. The joists are probably leaking air from the cavity wall. You will need to lift some floor boards and work your way round with some sealant and seal the gaps round the joists where they go into the external walls.

    Wait for a windy day then use a light feather and hold it in place near the floor and you will soon start to track down the gaps.

    Dont forget also round doors and windows and all service entries as well.

    Also check you have 300mm deep insulation in the roof.
    • CommentAuthornkmanglam
    • CommentTimeSep 26th 2007 edited
    Hello, Frank, Mike and Nigel,

    Thank You very much for your comments. I am delighted to get such a good response.

    I am glad that i joined this forum which saved me £XXXX on UFH.

    Do you think i can draught proof the house myself ? If yes what materials i have to use to seal air ingress on first floor void ? IS IT A DIY Project ? Can i do it from inside or do i need to take dormer tile off and insulate it from outside?

    Why my foor temperature is always 2 degree less on ground-floor floor compared to tremperature at 6 feet height on the same foor? Has it got something to with my big georgian front door (with side panel) which is not double glazed?

    I am contemplating getting this big front door changed into triple glazed. ANy feedback of triple glazed windows and doors ? i have read that triple is still the same thinkness 28 mm with k glass but it is more effective. I want to be future proof thats why i want to use triple glaze. but it is expensive compared to double glazing ANy feedback on triple glazing?

    Thanking ou


    • CommentTimeSep 26th 2007
    You should be able to draught proof most of the house but I suspect the dormer and underfloor void will be more difficult as you will have to first of all get access to the voids which will be the hardest part.

    Warm air rises so I would expect there to be a temperature differential between the top and bottom of a room, this will be made worse by the lack of floor insulation.

    As regards your front door although it is single glazed its probably a minor issue compared to some of the other causes of heat loss so I would leave it as it is until you have sorted the other problems first.
    • CommentAuthornkmanglam
    • CommentTimeSep 26th 2007
    Hello Nigel,

    Thanks again. I can get access by removing all carpets and wood floor on the first floor. because one side of dormer is only windows in three bedrooms and other side is bathrooms, landing, cupboard and ensuite which is not that bad but will get them draught proof once i start chaging bathrooms and ensuite.

    What materials should i use for draught proofing ?

    My current ground floor insulation is around 5-10 mm under chipboard. Do you think i should just upgrade this to 100 MM celotx insulation board? will that help and ofcourse will have th draught proof dromer walls and first floor void?

    Need to know what materials can i use easily for draught proofing ?

    Thanking You

    Kind Regards

    • CommentAuthortony
    • CommentTimeSep 26th 2007
    I dont think that you should trust anyone else to do going on past record.

    Do the ground floor later -- you should get good info on this using our search facility.

    The void between the floor and the ceiling must be air sealed. It will not be easy. The simplest way to do it though not the best, but likely good enough, would be to very tightly wodge insulating quilt in all the joist gaps immediately below where the outside 'dormer' walls are. At the same time add insulation to both the walls and the ground floor ceiling. Better method would be to additionally cut and fit a piece of plywood sealed on all four edges in line under the plaster of the wall. Quilt is not quite impervious to air but compared to what you have at present it close enough. Do not neglect the end joists which run parallel to the end walls and totally fill that gap full all the way along. The idea is to separate indoors from out and the loft voids count as outdoors I'm afraid.

    Come back and tell us when you have done that.
    • CommentAuthorchuckey
    • CommentTimeSep 26th 2007
    What I would do is to go upstairs and figure out which way the floor joists run. They run at right angles to the floorboards or flooring panels. Starting of in one room, go to the outside wall where the ends of the joists go into a wall. Lift the board or panel and inspect the seal of the mortar around where the joist go into the wall. If there is a gap squirt some sealer into the gap. If its very big, stuff the hole with old plastic bags then use sealant. At the same time look at the seal around any pipes or wires. Do the outside end of all joists. As mentioned, there will be a joist that runs about 2" from an outside wall, try and stuff this gap with WHY (glassfibre / plastic shopping bags. . . ). One good target would be the waste for the bath. sometimes they are drop down from the bath, theres a huge hole in the floor and the pipe then runs through another big hole(in the inner wall skin), to the outside where the pipe is neatly mortared in, cos it can be seen.
    • CommentAuthornkmanglam
    • CommentTimeSep 27th 2007
    Good Morning everybody,

    I had a local builder out yesterday to give me some idea. He has proposed me following :

    1. Take off existing inner plasterboard from both sides of the dormer and re insulate it with 100 or 125 celotex board and then put the new plasterboard then re plaster.

    2. When he takes off all plasterboard, he will also lift all floor panel and do draught proofing for both side of dormer void.

    3. He has given me an option that he might not need to do it from inside he can take off outside dormer wall and for some area dormer roof off and reinsulate it and re board it from outside.

    He will give me a price on this next week.

    When i spoke to my LA building inspector, they told me specificaly that all changes in external wall, roof and Floor are subject to building control. But this builder said i don't need to apply for building control.

    Should i get a structural engineer out and get detailed drawing and specification plan done so that builder just has to follow those specifications,. Or even if i wanted to DIY these work with help of my friends, i will exactly know what specification to follow. And as a specification by a structural engineer will be indemnified i don't have to worry about it too much.

    This is just to ensure that in few years time when i try to sell my house, i am fully complaint with HIP, as this a very big and unfortunately very expensive house.

    I want to maintain propoer paper work so that new buyer of this house feel comfortable.


    will await your valauble feedback.

    Thanking you


    • CommentAuthortony
    • CommentTimeSep 27th 2007
    No way should you need an engineer! If you felt the need a surveyor could be the person you need to help you with specification. Take lots of photographs of everything and new work and inspect everything before is is covered up again. Building control is likely but they dont care much more than lip service about air infiltration. Keep a very close eye on the work. Badly fitted sheet insulation can do less insulating than quilt because of the disproportionate effect of gaps.

    You must finish up air leakage free especially from outside to under the floor. There is little point in having expensive insulation in the walls if there is a howling gale from outside cooling the floor and the room. It probably blows out from under the skirtings even on internal walls!
Add your comments

    Username Password
  • Format comments as
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   

© Green Building Press