I am based in Crewe and bought a 1945 semi detached house that needs a bit of work to stop its energy leakage.
I have a reasonable understanding of retrofit and EnerPhit and I am very keen to modernise the house and reduce the energy consumption as much as possible.
However, but I am not an expert or builder and my budget is not enough to do a full EnerPhit. Iām just trying my best to do a good job on what I can do.
Only moved in a year ago and have now got some initial plans with an architect. Knocking through a kitchen-diner wall, remove a kitchen breast and most importantly to insulate all ground floor floors as well as doing my best to insulate the small 1980s kitchen extension. Unfortunately, the current ground floor is a suspended timber floor on one side and a concrete floor in the small kitchen extension! Of course neither is insulated, which. I want to change.
As you can maybe see, the plan is to do the dirty ground floor work in the house first this year so I have a place to live and then follow up with windows, roof and MVHR a bit later on when the budget allows.
As these are all kind of different works I am struggling a bit with where to start to look for builders that are interested and would be skilled around insulation and ground works as the soil pipe will need to be moved inside the house. Of course I am also looking for somebody/ or the same builder to remove the chimney breast and knock through the wall and redo the warm roof on the old kitchen extension. Not sure if this would all be one builder or if I should go with different onesā¦
Would be great to find a builder that knows already about the details of underfloor insulation, taping things up for air tightness etc and thought some people here may be able to provide some advise.
Christian
Like you Iām not a builder but did most of the work myself. It would be worth you getting on an airtightness course both People Powered Retrofit and The Retrofit Hub run courses locally.
We have suspended floors so my approach was to fill between the joists with insulation held in place by a membrane - I didnāt use a specialist membrane but would do now. A vapour open membrane so that airflow under the floor doesnāt enter the insulation.
Then we installed our airtight membrane on top of the floor boards, taped and sealed to the walls behind the skirting board. Plus a board over the membrane to protect it before fitting underlay and carpet.
Thanks Ian. I am definitely thinking I could do the insulation of of the suspended floor myself.
I got the drawings of the architect and good point in using a proper membrane below and and above. I have watched a lot of Youtube videos and I think it can be done.
What insulation did you use? Rigid or soft like mineral wool?
The suspended floor is not really my biggest headache, except some of the air bricks have been closed when an earlier owner put a conservatory on the south side. So I need to reinstate before I insulate without wrecking the existing conservatory.
However, the biggest headache is the uninsulated concrete kitchen floor, and getting the new soil pipes deep under that kitchen floor before before replacing it with an insulated floor. And finally I need to insulate AND extend the roof on the kitchen extensionā¦ to coordinate all of this with builder is a bit tricky and could easily blow my budget. However, just having a builder you can trust to do a good job and to know what they are doing from an insulation and air tightness point of view is I think key. Maybe the team from the Retrofit hub could do some of it, so letās keep fingers crossed.
A concrete slab is typically not a huge heat loss area.
You could put insulation on top of the slab, say 50mm if you can get away with it.
If you really want to step it up, consider removing the slab around the edge of the floor that has a perimeter to external wall. Try and bolster the insulation thickness here as much as possible. Of course the insulation need a solid base to below it.
Tear up the concrete floor and repalce it with some load bearing moisture resistant type insulation. but this will be costly and not overly beneficial.
Mixing a bit on concrete to and laying the insulation you can proabably do yourself. Given that both are cheap, you proabably several attempts before the cost comes to a builders quote. have the builder just do the waste pipe. and backfill with the appropriate backfill.
Overall the heat lost through a floor is generally less than for other components of a house. The losses are greater for a bungalow. However, comfort wise floor insulation makes a huge difference. Humans are most comfortable with their feet warmer than their heads.
There are a number of possible solutions.
Thoroughly insulate the floor
Heat the floor (very wasteful without 1.)
Dancing on the ceiling! As proposed by Lionel Richie nearly 40 years ago.
In all cases remove draughts by properly airtightening the floor. Even solid floors can have draughts, particularly at the margins and around protrusions.
How much hassle are you prepared to put up with? What is under the concrete? Are you in a flood risk area?
I am currently still living only part time at the house as my partner has her own house a bit away. I donāt have any kids, so really, I always thought if I canāt do the dirty fabric jobs like doing the floor insulation then who can? So I donāt mind the hassle. I am more concerned with the budget, but did want to do the dirtiest jobs in the first year. So removing the chimney breast, knocking through a wall, and doing underfloor insulation would be on that initial to do list. And the kitchen is one of the coldest rooms right now and when I knock through from the living room into the kitchen I really want that kitchen extension to be better insulated all around.
I have gotten some quotes for the kitchen windows and the doors that are affected by the floor insulation. My architect pointed towards making sure that the door thresholds are not a significant cold bridge. So it seems like something to upgrade and replace while you do the floor insulation and although I am not surprised, the costs are very significant (for proper Triple glazed stuff.
I am just getting more Window and door quotes and would appreciate any suggestions for good quality windows and doors that get U values of around 0.8.
So far I looked at NorDan, which seems nice, and I am still waiting for quotes from 21 degrees, Norsken and Neuffer. Are there any good British manufacturers of triple glazed timber windows somebody can recommend?
Anyway, I need to understand the costs of the building work to phase things appropriately, but if I do something, I would like to do it properly. If I canāt afford it now, I will just plan to do it later. So I really need a good plan.
Iām afraid I canāt suggest a British window manufacturer who would be interested in the job. When I was looking at windows I found a few that werenāt interested in one off retrofit work. I think they were after contracts to glaze entire new build estates.
NorDan is good. Also Rationel and Velfac, which are now both owned by the same parent company, Dovista. Rationelās approved installer list is (un)usefully in alphabetical order but not too long to search
Velfac donāt even publish theirs, you need to contact them for a referral
With regards to your question about the floor, I was lucky to be given the original drawings of the Kitchen extension from 1981.
Of course I canāt be absolutely sure if these were followed and exactly detail how the concrete floor was built. But it is great information. In terms of the soil underneath we mostly have clay.
With regards to floor risk, I think we are ok here. My flood maps didnāt show any risk and I think I am on one of the highest points on our street.
However, for the part of the house with the suspended floor, the previous house owner has put paving stones all around the house and raised the ground level above the air bricks, partially blocking them on one side and completely blocking them on the other (with the conservatory). So I will need to rectify this.
It isnāt clear from your drawings but I assume the floor height is level across the join between original house and extension. This limits possible solutions. Roughly speaking you have 3 choices. Measures that span the whole ground floor, measures that go below the current floor level or have a step up into the kitchen. My guess is that underfloor is the most appealing but is also going to be the trickiest to get right. That is what I would do, given that the house is currently empty.
According to the elevation you have 600mm to play with under the floor. That is more than you need to get top grade insulation in place. You could also move the soil pipe and any other services while the floor is excavated. If that means that you have 600mm free in the floor void too then the same solution can be applied to the rest of the house, replacing the suspended floor with a āsolidā one. The AECB recommend this approach where possible.
Here is a pertinent detail drawing for my house, work not yet done as I canāt persuade my wife of the benefits versus upheaval.
Yeah, I will see if I can find a good builder who wants to take this kitchen concrete floor on. It is about 10m2 of floor and will see how much work and cost that will be.
Indeed the floor is level between the extension and other areas. I donāt really want to have a step if possible.
In any case, while I would love to have the same floor all around the house I really want to keep my suspended floor in the living room. I just donāt want all that concrete and insulation between the joists should be something I can do which doesnāt have a massive amount of embedded carbon and canāt easily be modified. I think a suspended floor has just much more flexibility, but probably a bit higher risk in terms of getting the ventilation right.
If converting to solid floor you remove the joists, not fill the gaps.
Low carbon alternatives to concrete are available but at a price.
In Germany, and my extension, instead of screed over the insulation they use T&G chipboard. That is a cheaper lower carbon alternative but you still need a suitable base.
You could use the old floor as hardcore for the new subfloor. These days more hardcode is used and packed down than in the ā80s so even saving any old hardcore that can be salvaged you will still need to add to it.
That saves on disposal costs, cost of hardcore and it is a carbon saving too.
I didnāt mean concrete between the joists.
No, on the kitchen side I need to replace and insulate the concrete with a solid floor, but the rest of the house has a suspended floor where I can potentially do the insulation between the joists myself to save some money and protect my budget a little. Existing floor base.pdf (2.6 MB)
Ok. Understood. From the floor plan I see you need to replace concrete slab in part of the old house too.
You have a combined drain. Is that still legal in Crewe? Iām in the Thames Water area and it definitely isnāt. If you do major works that also involve the drains you may find that you are required to separate runoff from foul drainage. The former to a soak away and the later to main drains. This is part of the regulations to reduce storm overflows and discharges of raw sewage to waterways.
Check with your architect. Or just do it anyway, as the right thing to do.
It is hard to balance the costs and the energy/carbon savings. The difference in effort/time/money between sticking insulation over the slab, which apparently is a no go, as you do not want a step, and ripping up the slab is significant.
However as long as you are a handy hands on person, I think a lot of these tasks can be done on your own.
Removing the 150mm of cement and screed is not too difficult with a hammer drill or jack hammer. You would not have to take up the DPM, infact you could add another layer/check for holes. It should be double layer and taped. I would be surprised if it was.
I then agree with @Tim_Gilbert floating floor. PIR as much as you can fit and T&G osb3 (not standard chip board) on the top would be fine, leaving a tiny gap to the wall for expansion, that is hidden by your skirting. This taped OSB would be your airtight layer and should be taped to the wall. And meet your wall airtight stretegy. Plaster i presume. Or a smart membrane coud go bewteen the insulation and OSB to do the same job. Then your finished floor goes on top.
The amount you can fit depends on your required floor finish.
If you really want to know how the savings are going to be then you need to model the project with PHPP. You can see then the overal energy saving per year for the extra work time and money you have spent on the house. It is all well and good doing this element of the house amazing. But if the rest of the house isnt up to a similar standard. Energy takes the path of least resistance across the temperature gradient.
So my question isā¦ will the rest fo the house come to the same standard eventually?
Have you considered modelling?
Yes, the concrete slab is in the whole kitchen, probably as they filled it up to the underfloor walls when they built the extension.
Interesting about the drainage. The architect drawings currently on concerns themselves with the soil stack movements, but yes this is a combined public drain. The neighbourhood is from 1945 and I canāt really see where all the runoff could go if not into the combined drain. Some of it may go into the garden, and I plan a railway collection system, but the architect has not mentioned anything about separation so far. The plans have been with building control as well and I havenāt seen anything come back from there either.
Though, I do have a plan for a green roof for the kitchen extension as they do have to redo it anyway. That will slow drainage a little from the flat roof.
So I donāt think this is a legal requirement here to separate runoff, but I will check.
I am trying to do a whole house strategy, and will replace windows in the whole house and probably do EWI as well at some timepoints.
My philosophy is that I do whatever I do to a high standard and in line with the whole house plan even though I might not be able to finish all of it by my own I will still have all the drawings and either myself or the next owner can then do the next bits when they have the cash.
In general the retrofit plan focusses on underfloors, and some external insulation and windows on the kitchen initially.
Then all windows will be done eventually with triple glazing. Then an MVHR, a heat pump as well and the roof will be done. These are already massive costs for me, but I take it one at the time. Will need some money also for kitchen and bath ā¦
Air tightness will be done for each job, but you are right there will be some areas of the house that will become new heat sinks until I get to it. Hence the MVHR will be important soon to prevent any cold issues if airtightness increases.
