Renovation of a '60s bungalow

[tjure2k]

Hi, first post here.

My wife and I are about to exchange contract on a detached bungalow built in the 1960s and are planning to give it a thorough overhaul. The structure of the bungalow appears to be very sound, but the heating and insulation really need some modernisation.

 

In particular, we would like to:

• demolish the porch near the kitchen and extend the kitchen 2m into the garden
• insulate the concrete floor, by excavating the concrete slab
• install an underfloor heating throughout the whole house
• replace the existing oil boiler with an air source heat pump
• replace the hot water tank with a hot water cylinder (with 3x coils to be compatible with an ASHP, solar thermal collectors, wood burner)
• insulate the loft (between and under rafters)

 

Potentially later:

• MVHR
• install a wood burner and connect the back boiler to the hot water cylinder
• install solar thermal collectors, connect to hot water cylinder

 

To reduce the risk we are thinking of doing this in two stages. We are planning to live in the small annexe (right hand side on the floor plan) while the work to extend the kitchen, excavate and insulate the floor in hall, living room, kitchen, main bathroom and bedroom 1 is being carried out. This is also when the ASHP and the hot water cylinder is installed.
In the second stage we'd continue the excavation, insulation and installation of the underfloor heating in bedrooms 2 and 3, the kitchenette and the smaller bathroom.

This is quite a bit of work, and we are rather inexperienced in this, so I'm looking for some feedback how realistic this plan is, potential problems and how long this would realistically take (waiting for the builders to be available, the new concrete floor to dry, etc). Would it make sense to hire someone to manage the project for us?
We did some research and found companies that rent electric boilers for the time we are living in the annexe. Is this a sensible arrangement?

I had a chat with a builder who advised against excavating the concrete floor and to use some thin insulation on top of the existing concrete. We think it would be beneficial to insulate properly (as it was also the biggest item in the EPC) and if we don't do it now, we probably won't do it later.

 

I'd be grateful for any feedback.

Thanks

[Ferdinand]

I did a thread about a 1960s one here. Not quite the same, but some stuff will be useful - especially perhaps my non-intrusive way of running services.

 

Does it have asbestos?

 

Have a look at raising the door heights (depends on ceiling) and putting in say 100mm of Celotex over the slab. 

 

 

 

[tjure2k]

Thanks Ferdinand for your reply, I rather enjoyed reading through your thread of the renovation of the bungalow, it turned out quite nice.

We also aim to turn the bungalow into a house that doesn't cost a lot to heat. The driving force is more the intolerance of the missus against drafts and cold spots. I take a dislike to damp, and luckily the house seems not to suffer from any noticeable damp. (The MVHR planned for one of the later stages should reduce humidity further.)

 

Luckily we don't appear to have any asbestos in the house. We had 8 samples taken and to our surprise they came back all clear (NADIS) except for a cold water tank in the loft (£250 quoted for removal). The Artex ceiling and the roof tile undercloak came out clear, even though the homebuyer's surveyor was quite sure adamant the under cloak...

 

The rooms are 2.36m high, which is already close to the recommended height of 2.33m, so we are quite reluctant to take any more height away. We don't plan to move from this house, so we are prepared to spend a bit more to get the floor insulated properly. As long as the costs stay reasonable.

[rh2205]

We renovated a 1960s bungalow (well almost destroyed it by adding a new storey on top), we didn’t have anyone to manage it just got a reputable (& well priced) small builder to do it. I’ll be honest we had to go around trying to patch up any of the “that’s how we’ve always done it” approach, but in fairness our architect did rubbish building control drawings and really a lot more detail was needed to avoid us having to go in at midnight and tape things like insulation because it wasn’t allowed for. We didn’t dig up the floor, well we dug up the screed ourselves & then realised it was only 2.5cm thick ?. Had the same height ceilings as you, in the end we compromised stuck in oversized radiators with the pipe work in the walls & externally insulated the outer wall plus had the cavity filled and installed an ASHP rather than a relocated new oil boiler as no gas. We haven’t put the heating on yet and it’s by far the warmest house we’ve ever lived in (husband keeps talking about aircon) but there is a temp difference between new upstairs and the downstairs probably because of floor but we also have convection log burner in a very large portion of the open plan downstairs so Im not worried. I think the bodge would of been to of put 70mm of insulation down & accepted the lost height & less efficient heating, but I was advised with a large slab like ours we’d be lucky to get 20k back from replacing the concrete floor and I was worried about the ASHP not heating it at all if we went with underfloor heating insulation bodge. Our costs came in at £1200sqm we only kept one section of internal wall and pretty much other than slab, foundations and external walls nothing else was salvaged. Surprisingly out of that we got 50sqm of aluclad windows. I do think we were lucky and our builder underestimated things but we also cut corners on some areas for instance our floor finish downstairs is laminate and we have a howdens kitchen (with quartz worktops).

Edited October 12, 2021 by rh2205

[James Newport]

Fellow sixties bungalow renovator here...

 

Digging up the floors and relaying will be expensive, but it's the best option in terms of performance, and for the finish of the floor. Inscreed UFH is far, far cheaper than the overlay systems as well, so it's worth factoring that into your decision making.

 

Living in half of the house while the other half is renovated is hard work. The dust gets everywhere. Crap gets piled everywhere. Fridges get blocked off by piles of insulation and then have to be sent off for industrial fumigation when you finally can access them again. If you go for this approach, stick as much of your stuff in storage as possible. I turned our large converted garage into a storage unit using shelves built out of the old internal doors, and it was still a struggle. 

 

Consider all your pipes and electrics up front. You don't want to finish one half of your build, and then realise you need to add something that's needed in the other half. 

 

Even if you hire a project manager they will still your time to make decisions. I managed ours myself, but it does take up A LOT of time. There was a period of a few months when I was pretty much full time on it. 

 

Think about external wall insulation. I didn't do it for this project, and with gas prices what they are, perhaps I should have...

[rh2205]

Yes I should add we didn’t live in ours until floor coverings were down, I mean it would of been hell/impossible because of the new roof thing too & we have a little boy. I am glad we didn’t live in it. Guess it depends on how strapped for cash you are, we rented a 1 bed flat which even with a child was by far the best idea & so it was the compromise of somewhere normal & vaguely affordable to live just a bit on the small side but just down the road away from the mess and noise. Infact thinking of anyone we know who has done a massive renovation that involve extensive works & new floors none of them have stayed in the house whatever their financial circumstances, everyone finds a way to leave except some crazy people on here & on the tv ?.

Edited October 12, 2021 by rh2205

[Ferdinand]

@tjure2k

 

Two more things I need to say. 

 

1 - Take a *really* serious look at doing a newbuild not a rebuild. It will give a better result, exactly what you want and may well (often the clincher) be more cost effective due to no VAT and no CIL (if you are 'eligible' to pay it.).

 

2 - 

3 hours ago, rh2205 said:

We haven’t put the heating on yet and it’s by far the warmest house we’ve ever lived in (husband keeps talking about aircon) but there is a temp difference between new upstairs and the downstairs probably because of floor but we also have convection log burner in a very large portion of the open plan downstairs so Im not worried. s).

 

 

Issues around cooling on well-insulated houses can be huge,  and is a major theme on BH.

 

At one level you can eg get a reversible ASHP,  but it needs to be a KEY element of your reno or build. 

[rh2205]

Our guesstimated costs were touch and go in relation to keep vs rebuild we felt like we were on the fence however we accidentally bought a empty property too so we paid 5% VAT (our plot had outline planning for 2 houses but a crappy covenant for one house so you get why it was still a massive consideration at the time). It is not everything a new build can be so @Ferdinand is right but then that also means you might choose to make more compromises on the existing structure which often are a saving too, however it does still feel like we live in a new property even if it’s not perfect we are still over the moon and our route definitely worked out in duration, end result and costs for us. If you can compromise on things that are expensive or do loads yourselves then a refurb might still be the way. And just to warn you at tender we had a price variation of 150k, that’s a 75% price variation from the 6 responses so there is always a finger in the air guess from the other side too!! No wonder we really didn’t know what it might cost, nobody else was really sure either ?. 

[Mr Punter]

If you have the money to do it, get it all done now.  Living on a building site is a nightmare and life is short.

 

Excavating the slab and adding lots of insulation is a good plan but expensive.

Consider external wall insulation.

For the roof, 370mm loft insulation is fairly cheap and simple to install.  Between and under rafters PIR is tricky and more expensive.

Forget the woodburner unless you want drafts and pollution.

Consider solar PV instead of thermal as the energy produced is more flexible.

 

Once you have decided, may want to get a specification and costings done.  If it look horrendous you can trim some things back.  Maybe get a few builders to quote for the main works and leave them to project manage.

[rh2205]

Mr punter is a very wise man life is short. Consider how you feel about lost time on any route, this weighed heavily on our minds during decision making. To give you an idea of time ours was 2years including plan making, planning permission, building control and a 9month refurb time which stayed exactly the duration the builder quoted for, he was a good kind builder that trades would come back and work for and not let him down. We actually had this builder on site within 3 weeks of our tender deadline, that sort of timeframe for someone competent is unheard of but it was just right time right place for a small builder who wanted an empty property during covid. You may get lucky with trades you may not, our friends have just moved into their refurbished property after 2 years of trades on site all subcontracted which is not the route we took but there main carpenter was someone they went to school with and had a lot of advice from too so I don’t think they were getting messed around. This is just the reality of the subcontracted route or just a bad builder who has taken on too many jobs!

[Ferdinand]

You may get your loft insulation free if you play your cards right.

Find your local ECO3 organisation, and do a touch of homework.

 

Plus: an example of how to approach cost control / optimisation:

 

 

[Ferdinand]

4 hours ago, rh2205 said:

Our guesstimated costs were touch and go in relation to keep vs rebuild we felt like we were on the fence however we accidentally bought a empty property too so we paid 5% VAT (our plot had outline planning for 2 houses but a crappy covenant for one house so you get why it was still a massive consideration at the time). It is not everything a new build can be so @Ferdinand is right but then that also means you might choose to make more compromises on the existing structure which often are a saving too, however it does still feel like we live in a new property even if it’s not perfect we are still over the moon and our route definitely worked out in duration, end result and costs for us. If you can compromise on things that are expensive or do loads yourselves then a refurb might still be the way. And just to warn you at tender we had a price variation of 150k, that’s a 75% price variation from the 6 responses so there is always a finger in the air guess from the other side too!! No wonder we really didn’t know what it might cost, nobody else was really sure either ?. 

 

Of course Ferdinand is right. Bah humbug as if it needs mentioning !

 

Everyone knows that except for:

 

(... List of 4752 named individuals removed for Data Protection reasons ... the Mods)

 

 

[tjure2k]

Thanks all, this has been amazing feed-back all round so far, there is plenty for us to think about.

 

We are definitely considering adding external wall insulation. We were planning of live in the renovated house for at least one winter before going down that route. The house has cavity wall insulation and the annexe has internal wall insulation, so we might find that we don't need the additional layer around the house. Our primary aim is to get a warm and cosy house, and not necessarily get it down to passivhaus levels, so we might find we don't need to do that in the immediate future.

 

The loft is already insulated (cold loft, using a blanket insulation) but would benefit from some better insulation. The windows are double glazed, and have obtained a good rating on the EPC and the homebuyer's survey, but might need looking at again, once the floor is no longer the main leak of heat in the house.

 

We also have briefly considered a new build, but we think this might be much more expensive than refurbishing it. The previous owner who was also the builder of the house has done a decent job and the house seems to be in a very good and solid state with a layout that works very well for us. Knocking it down seems a bit of a waste. We might though talk that through with an architect to get a better understanding of the costs involved.

 

The common suggestion, I see, is not to live in the house while the work is ongoing. Our main reason (apart from costing) is that we currently live 40 minutes from the bungalow, and being able to meet and talk to the builders on site would become a logistical problem. We are now adding the cost of a nearby rental to our budget, but we hope it won't be 2 years to finish the works. ?

 

Eliminating the wood burning stove from our plans is a non-starter, I'm told in no uncertain terms by my wife. ? We are not dead-set on the back-boiler but like the idea of having a fall-back for very cold days when the ASHP might be struggling.

 

Thanks again for all the suggestions.

Edited October 12, 2021 by tjure2k
Spelling, missing words

[Deejay_2]

We are considering remodel of 1970's bungalow.  Isn't there a saving to be taken into account over new build of the cost of groundworks.  We built on a separate plot on the same site in 2015 and our groundworks up to the block and beam floor cost us £31,000 plus demolition and initial boreholes, soakaway reports etc. 

 

We would like to extend the bungalow outwards involving two whole external walls (new footings) and will more or less end up with two breeze block (may be brick) external walls  still standing - so almost full demolition.  Then remodel internals, new roof etc with rooms in roof.  This will allow us to choose an external building material to match the other two new house on the site, and install insulation as required, ufh, etc etc.  Does that sound doable.  We are in a Conservation Area and feel doing it this way will require less restrictive input from Planning.  

 

We have a small competent small builder who would do the work but who is not interested in doing a new build so lot's to consider.

 

 

[Iceverge]

On 11/10/2021 at 21:23, tjure2k said:

demolish the porch near the kitchen and extend the kitchen 2m into the garden

Have you considered knocking the chimney and the wall between the kitchen and the living room and making your kitchen larger this way. Much cheaper than an extension.

 

On 11/10/2021 at 21:23, tjure2k said:

insulate the concrete floor, by excavating the concrete slab

You could put external insulation down to the footings and out. This should bring the floor inside your thermal envelope. No need to dig. 

 

On 11/10/2021 at 21:23, tjure2k said:

 

 

 

On 11/10/2021 at 21:23, tjure2k said:

install an underfloor heating throughout the whole house

As an alternative consider floor coverings that aren't cold to the touch like tile and stone. Use LVT, lino, carpet, laminate or wood instead. 

 

On 11/10/2021 at 21:23, tjure2k said:

replace the existing oil boiler with an air source heat pump

 Don't be too hasty on this. ASHP isn't a panacea. Concentrate on minimum heat demand first.

 

On 11/10/2021 at 21:23, tjure2k said:

replace the hot water tank with a hot water cylinder (with 3x coils to be compatible with an ASHP, solar thermal collectors, wood burner)

 

Tricky and expensive to combine all. I would discount solar thermal and a wet stove. Their day has passed. 

 

On 11/10/2021 at 21:23, tjure2k said:

insulate the loft

Good plan. 

 

On 11/10/2021 at 21:23, tjure2k said:

MVHR

Probably should be the first thing you do before you insulate. 

 

My mantra for proceeding. 

 

1. Sort any bulk water issues.

2. Ventilation (preferably continuous mechanical, ideally with heat recovery)

3. Airtightness (cheap and hugely effective)

4. Improve u values.  (Including windows) 

5. Consider your heating system. 

6. Renewables (PV)

 

If you are determined to have a wood burner, get a small one. ( They make the house colder when not in use and like asbestos leave plenty of nasties in the internal air)  Put it in a central area. Use a proper insulated flue and run it hard when in use. Don't connect it to the water. Just open a few doors to heat the house. If logburning is a lifestyle you enjoy and are committed to it long term @Thedreamer has a nice setup with an EASHP. 

 

 

 

 

Edited October 17, 2021 by Iceverge

[tjure2k]

This is all good advise, and we took a few days to mull over it. We came to the conclusion to put electric panels on the roof eventually, and not to pursue the wet stove. A stove is still a must, as we like the idea of having one in the living room, so that is more a lifestyle choice. We hope we can find an airtight model, so we won't have much heat loss when it is not fired up.

 

The external insulation is a good thought. We had this in the plan, but for later, if it is needed. We didn't think to dig down that far, but I guess it will be beneficial/necessary to get the expected results. Would it make sense to sink a french drain, just in case, since we would have a trench dug out for the external insulation? (I'm not aware of any damp so far.)

 

However, we also think the floor needs insulating rather sooner than later. That is some big and dirty job, so we think we would end up not doing it if we delay it for later So we probably still want to get this done first, even if it is not the optimal order of events, technically speaking. As the house has some cavity wall insulation already fitted, we hope that we will make it through the first winter and then decide what is next.

 

What is the reason to do the MVHR before any insulation? We thought this is a relatively minor job (it's a bungalow, and all the ductwork can be done in the loft) and so can be done at a later stage.

 

Thanks again everybody for all the good feedback, we are still reading up on the various hints we got, and keep changing our minds on a regular basis on these things, as we are both inexperienced. ?

[Iceverge]

3 hours ago, tjure2k said:

We hope we can find an airtight model

I would just fit a conventional good quality one unless you end up with extract only ventilation. There'll be plenty of air in your house to feed the stove. No need to put in more holes. 

 

3 hours ago, tjure2k said:

We didn't think to dig down that far, but I guess it will be beneficial/necessary to get the expected results

 

It does help. I'll try to show with some Therm simulations adapting my own 250mm eps cavity wall.

 

 

 An approximation of external wall insulation only. Total interior U value 0.49. 

 

 

 

 

 

 

Now with 200mm EPS in the floor. U value drops to 0.3 but still lots of heat escapes via the corner if insulation is not carried down. Bearing in mind this is with a wall U value of about 0.13 and a floor of 0.16 so the effect of the thermal bridge is dramatic. 

 

 

 

 

 

 

 

 

Look what happens when we carry the insulation 700 mm below floor level. U value drops to 0.2.  A big improvement. 

 

 

 

 

 

 

 

The same but with floor insulation removed. U Value back to 0.34.

 

 

 

 

 

 

 

Next I've added 1m of 100mm EPS horizontally. The floor U Value is now the same as with just the 200mm floor insulation and nothing externally below ground. (this is a simplistic example so they wouldn't perform the same in reality. BTW I've also accidentally removed the outer leaf here but it makes little difference)

 

 

 

 

Finally I've done all I can to avoid digging the floor, Externally insulated with 250mm EPS 700mm below the ground. Included a 1m wing and added 25mm of EPS above the floor to take the underfloor heating pipes. U value is 0.27 overall. I'm going to make a crude estimation and say this is the equivalent of putting 250mm EPS in your floor and not taking any measures against the wall/floor junction. 

 

 

 

 

 

The lesson of all this is 2 fold, firstly if you can't or really don't want to dig up your floor there are other options.

Secondly insulation is of limited use without getting a handle on thermal bridges. 

 

 

3 hours ago, tjure2k said:

Would it make sense to sink a french drain

 

If you search for "french drain" I did some posts recently about them. I think everyone should have one. 

 

3 hours ago, tjure2k said:

all the ductwork can be done in the loft) and so can be done at a later stage.

 

It'll be a pain with the insulation already installed and if you put in batt or roll insulation you'll never fix it right again after putting in the ducts. 

 

 

Hope this helps. 

 

 

 

 

 

 

Edited October 25, 2021 by Iceverge

[Ferdinand]

On 12/10/2021 at 21:22, tjure2k said:

We are definitely considering adding external wall insulation. We were planning of live in the renovated house for at least one winter before going down that route. The house has cavity wall insulation and the annexe has internal wall insulation, so we might find that we don't need the additional layer around the house. Our primary aim is to get a warm and cosy house, and not necessarily get it down to passivhaus levels, so we might find we don't need to do that in the immediate future.

 

Both Airtightness and EWI are *all* about detail, detail, detail. EWI especially is also about careful planning. You need to be obsessive about it.

 

I'm not sure I mentioned it in my thread, but you would need to specify deeper external windowsills so that they stick out over any potential EWI. Cheap if you do it when you do the windows; a pain if you forget.I think I specced either 200mm or 250mm. Also for door thresholds, which I detailed with support for when people stand on them.

 

Inside a classical example of a cold bridge that gets forgotten when doing IWI is the wall strip between the two floors (does not apply to you, but remember you have similar potentially under your floor).

 

One way to think about it is where your insulated envelope runs. In the Little Brown Bungalow I made it beneath the internal floor, and up the walls where I had CWI, and on the loft floor. So I actually ran the plumbing and electrical services under a floating floor to keep them fully inside it. That meant I maintained the airbricks to keep the joints ventilated and dry.

 

In the end I did not do EWI, as it was already good without it, even though my walls had a poorish U-value. The only wall I dry lined was with the other half of the semi-detahced pair, and that was for sound not heat reasons.

 

F

[riboid]

I would not even think about a wood burning stove (my wife wanted one initially) if you are trying to target good insulation and air tightness values - in fact, building control may tell you not to do it (they did for me) and anyway, it was just a passing thought.  Wood burning stoves burning in your living room is the equivalent of having a diesel truck in your house and will render the air quality rubbish and if you are putting in a MHVR to improve air quality, it is quite contradictory.  We are just about to finish our 1930s bungalow and it wasn't for the faint hearted.

 

Good luck.

[Ferdinand]

31 minutes ago, riboid said:

I would not even think about a wood burning stove (my wife wanted one initially) if you are trying to target good insulation and air tightness values - in fact, building control may tell you not to do it (they did for me) and anyway, it was just a passing thought.  Wood burning stoves burning in your living room is the equivalent of having a diesel truck in your house and will render the air quality rubbish and if you are putting in a MHVR to improve air quality, it is quite contradictory.  We are just about to finish our 1930s bungalow and it wasn't for the faint hearted.

 

Good luck.

 

If you do go with that, many people in good quality houses end up looking at stoves for caravans or boats as anything else makes it unbearable in no  time at all.

[riboid]

Yeh, all sounds nice, cosy and attractive but kind of veers away from what we (sustainable houses) are trying to achieve.  Minimal impact on the environment etc.

[joth]

19 hours ago, Iceverge said:

. Included a 1m wing and added 25mm of EPS above the floor to take the underfloor heating pipes. U value is 0.27 overall. I'm going to make a crude estimation and say this is the equivalent of putting 250mm EPS in your floor and not taking any measures against the wall/floor junction. 

 

 

 

 

 

Are you aware of anyone who has done the external horizontal wing? It was a detail on our plans, but our builder really wasn't happy to install it as they felt it wouldn't be very robust and likely cause whatever is above it to subside.

We could still achieve Enerphit without it, so it was removed

[Iceverge]

Americans.

 

https://www.jlconline.com/how-to/foundations/a-frost-protected-shallow-foundation_o

 

 

1 hour ago, joth said:

It was a detail on our plans, but our builder really wasn't happy to install it as they felt it wouldn't be very robust and likely cause whatever is above it to subside

 

Your builder needs to do more reading, it'll make him happier.

EPS can be used in lieu of ballast in supporting railway lines. 

 

Edited October 25, 2021 by Iceverge

[ADLIan]

Its been a while since I used THERM but those GF U-values do not look correct - the U-value is more dependent upon the size, shape and edge conditions of the slab (plus any insulation). I would expect the ground floor of a 'typical' dwelling to have a U-value of approx 0.12 W/m²K with 200mm of EPS in it, adding vertical edge insulation would be of little benefit to the U-value in this instance. With no insulation the U-value would be approx 0.65 W/m²K, adding vertical edge insulation perhaps reducing this to 0.45 W/m²K. The external wing insulation would probably have little effect on the U-value - it is more for frost protection in colder climates.

 

[joth]

12 hours ago, Iceverge said:

Americans.

 

https://www.jlconline.com/how-to/foundations/a-frost-protected-shallow-foundation_o

 

 

 

Your builder needs to do more reading, it'll make him happier.

EPS can be used in lieu of ballast in supporting railway lines. 

 

 

Interesting! 

To be fair, it was the PH architect that authored the detail but couldn't back it up with evidence on longevity of the construction. IIRC the detail on our plans didn't mention what base the EPS should be laid on, which would be a lot of the issue.  Either way I can see this would be easier done on a new build than a retrofit around existing founds, as ours was.

 

Thanks