Full house renovation and retrofit guidance

[fisnik]

Hi there.

We're going to do a full house renovation including to the rear and side (2 story wrap around extension) and loft. As you can see from the pictures there's already an existing single story side extension. We'll be adding another level to it on top and extending to the rear too.

All the family will be moving out and the house will be entirely gutted to the brick so it's ideal to install any insulation and whatever else possible to make it as energy efficient as possible whilst the works are being done.

The problem is the budget I was envisaging whilst substantial it will be mostly eaten up by the extension (probably). I don't know how much funds we'll have left to do a lot of the intensive adaptations (like super tight airtightness, MVHR, also dig up the concrete floor and insulate). Getting an idea of what materials and methods and their cost, might help to decide what we should drop out from doing. Current original fabric of the house is solid walls 1930s built.

Just on the face of it what kind of insulation specifically I would be looking at in terms of what materials, internal or external insulation or a combination of both? Although it would be nice, hitting EnerPhit levels I imagine it would probably be too costly and impractical, but I'd like to get some way towards it if I can and if I can do it on the cheap and do some of it myself I'm up for the challenge. Even if it just enough so I can go for a heat-pump and not worry that it's going to cost me more than my current gas boiler in bills. Dream is to have solar, battery and heat-pump and disconnect the gas. (I may need more help later with this aspect later on) 

We're about to re-submit our planning application as we had a hiccup and were rejected, the plans that I've attached are more or less what we'll be ending up with though. I'll still be getting quotes from builders etc but I'd like to have plans in place that include the insulation aspect.

Any guidance is much appreciated.

House extension plans.pdf

[JohnMo]

If you can only afford to do the extension why are planning gutting the house as well?

 

Cut your cloth according to budget.

 

I would have an air test done and ask the guy to spend a hour going around the house finding and identifying air leaks first. Then make a plan of action to fix. Understand your current insulation and see how to upgrade cost effectively. Lofts are easy to upgrade, floor? (New floor or insulation to original), walls? (Internal or external)

 

You plans have zero details on build up of walls, roof, flour etc, so are just a pretty picture. To get what you want the builder needs to quote based on exact specs, hoping for the best isn't going to get what you need.

 

If you aren't airtight don't bother with MVHR, a well designed MEV or dMEV system will be more appropriate. And cost many thousands less.

 

I would step back and get everything planned and realistic to your budget.

 

 

[Redbeard]

Welcome.

 

What's the orientation? Is it conducive to solar? Do you have plans for PV?

 

I assume the house is of cavity construction. is the cavity insulated? If money is tight I am not sure how keen you'll be to completely remove the bays and 'plant' new bays on top of EWI. EWI also needs care to avoid the risk of thermal by-pass via the cavities. 

 

If you were to go for internal insulation (IWI) you'd be limited as to what U value you could achieve, due to the risk of interstitial condensation. Detailing can also be tricky depending on the internal layout. On the other hand, assuming you do not own the land to the right, I'm not sure how practical EWI would be, either. Ideally you need to find a way to use one or the other, or a mixture of both. If perchance, there are 'viable' (50mm+ and 'clean') cavities and they are uninsulated, start with that, with EPS beads (not mineral wool, in my view).

 

 

[Redbeard]

I was typing while @JohnMo was posting. His points are very valid. Why rip out if you cannot afford to re-do? If the potential cost is completely unaffordable why not ask for a staged plan?

[fisnik]

Thank you @JohnMo and @Redbeard for the messages. The orientation is the frontage you see in the photo is south facing. It's nearly perfect south. 

 

Perhaps I should have explained. The house needs "gutting" because everything internally is really old. Artex ceilings, textured wallpaper, exposed central heating pipes, kitchen units falling apart, non existent wall sockets upstairs with old grey style metal consumer unit that is not fit for modern age. It will need full rewire and full new plumbing, new kitchen, new flooring, new everything. 

 

We're a family of five living here with three young children and we need to modernise our home. We bought it with the view of extending. Two of our children are special needs. Our 9 year old son is profoundly Autistic with high needs and will be living with us for the rest of our/his life. We're looking to add a sensory room for him. We will also potentially have grandparents move in once extended as they currently travel in every day to help out with the children and taking them to and from school. Me and the wife are both working full time. That's the reason why we're looking to increase the size of the house as much as we can. Also we need to alter the living space to open plan as we need to oversee the children and have line of sight. Our boy can really go for our toddler if he feels annoyed or any noises are made.  😩

 

In terms what would be a priority is renovation>extension> energy efficiency (insulation, air tightness, solar and battery for bill savings). The aim is to do it once, do it as best we can and we chose to wait and do it this way instead of having a mish mash of renovation and constant upheaval where you're doing a bit at a time. We're lucky that some years down the line after buying we can afford to do this now without putting ourself out financially.

 

The drawings posted are just for submitting planning and not detailed. I will be having detailed construction drawings from my architect once we get the planning accepted.

 

In terms of insulation the only old fabric of the house will be the frontage you see there. and the wall of the existing side extension of ground level. Hoping to do some trial holes and hopefully the foundations are good enough to add the second story on top. The house is definitely solid brick. The existing side extension is cavity wall from the 90s I expect (previous owners built it). I'll have to see if there's any existing insulation within it. I am mindful of this but I'm hoping to fill that cavity with beads. The access road is shared road for garages so strictly speaking I'm not allowed to put anything on the side externally but realistically maybe just 50mm EWI may not ruffle any feathers. The main neighbour that has most of the impact said he was fine with it.

 

From our calculations we have the funds to do the renovation and extension as seen on the drawings and that is the priority. But with what would be left over also we like to get the best cost/benefit analysis in terms of energy efficiency/insulation and eco friendly aspects to our build. Currently we're hoping to not get a loan out but if something is worth it we will.

 

 

[Redbeard]

10 minutes ago, fisnik said:

maybe just 50mm EWI may not ruffle any feathers.

 

I realise you will probably be there for life, but just in case you ever need to sell, might I suggest that you try to 'buy' that 50mm? A client of mine did exactly that, though they at least knew who owned the land. In the case of a 'shared road' it may not be so straightforward to find the 'owner' to buy from.

[fisnik]

21 minutes ago, Redbeard said:

 

I realise you will probably be there for life, but just in case you ever need to sell, might I suggest that you try to 'buy' that 50mm? A client of mine did exactly that, though they at least knew who owned the land. In the case of a 'shared road' it may not be so straightforward to find the 'owner' to buy from.

I know who owns it. It would be all of the 8 properties that have access to it on the deeds. So I'd need to buy it from the 7 other homeowners. Don't think I'd be able to deal with the paperwork that would need. I was told that apparently you can get a party wall agreement and put all other 7 on it and that "might" be okay but I'm a bit weary of doing that too.

Edited 18 hours ago by fisnik

[Gus Potter]

6 hours ago, fisnik said:

We're going to do a full house renovation including to the rear and side (2 story wrap around extension) and loft. As you can see from the pictures there's already an existing single story side extension. We'll be adding another level to it on top and extending to the rear too.

All the family will be moving out and the house will be entirely gutted to the brick so it's ideal to install any insulation and whatever else possible to make it as energy efficient as possible whilst the works are being done.

Good stuff!

 

2 hours ago, fisnik said:

We're a family of five living here with three young children and we need to modernise our home. We bought it with the view of extending. Two of our children are special needs. Our 9 year old son is profoundly Autistic with high needs and will be living with us for the rest of our/his life. We're looking to add a sensory room for him. We will also potentially have grandparents move in once extended as they currently travel in every day to help out with the children and taking them to and from school. Me and the wife are both working full time. That's the reason why we're looking to increase the size of the house as much as we can. Also we need to alter the living space to open plan as we need to oversee the children and have line of sight. Our boy can really go for our toddler if he feels annoyed or any noises are made.

To me this is the key and will drive the design as you state. Forgive me if I come over as a bit blunt / appear to lack understanding, it's not my intention. Fundamentally you have your kids design requirements, potentially grand parents moving in.. (but unfortunately they will not be there as long as you and your kids) and of course your requirements. I very much admire what you are doing. 

 

I can @fisnik see that you want energy efficient home.. but there are different ways to skin this cat..

 

Ok, I've had a look at your drawings and visuals which look good. I'll outline my though process. Of course I know you have already put lots of thought into this but often and, this is the great thing about BH is that you get folk commenting.. they see things for the first time and come up with opinions.. sometimes they are wrong! If so that's good as it gives you confidence you are on the right track.. call it due dilligence. Other times they are right and folk realise they have dropped the ball!

 

I've started by reading your requirements again and put my SE hat on first. A number of things flag up. 

 

1/ You are creating a big open plan space on the ground floor and taking away a lot of the sideways building stability elements. This is to to with when the wind blows on the house and want to push it sideways. You'll need some steels in there to hold everything up above. One end of the steels is hard up against the party wall.. lots of vertical load and to stop over stressing things at the party wall is likely to entail a fair bit of cost. The steels will also need to be deisnged to stop the building moving sideways and as you move up the floors you also likely need some complex structure. There are other structural and costly things that flag up but I'm not going to detail these here for simplicity. But I can see many.. cost / build programme risks!

 

2/ Much of the wall arrangement on the first floor is offset from the ground floor which makes the load transfer more complex. There is chunk of the existing masonry wall at the gable left in place. Takes up space and is heavy. 

 

3/ The roof is then a fairly complex shape and all that needs to be supported. 

 

Conclusion on the above. 

 

While I could design a structure to work for you I just know a few things deep down!

 

1/ I might feel guilty when I submit my fee! A structural design for this will need to be very detailed, with explicit instructions to the contractor. If it's not like this then the Contractor will go off and do their own thing and you'll end up paying for something that is not adequate. A very big dispute can easily take place. I can see that to make something like this work structurally is likely going to cost you more than you are aware of at the moment. Don't blame yourself for this, you have no way of knowing!

 

2/ You'll have to be able to make sure you are able to supervise the works and have in place an agreement as to how you deal with the unexpected. 

 

3/ What you propose comes with lots of "Architectural risk" ( the Architectural details, potential for an inexperience Architect , or you are not paying enough for them to do this work) contractual risk = money and a potential huge amount of stress. You have enough on your plate and are already carrying lots of responsibility. I would encourage you to say.. let's try and set this project up to de risk it and aim to have fun doing it, then enjoy that quite satisfaction that you made informed descisions. 

 

4/ Adding another story at the boundary ( lane side) could well entail strengthening of the existing founds.. work on that assumption for now to be safe. 

 

My next thought process:

 

Good design is about iteration. You revist the earlier descisions you made to check they are still valid and you are not dropping a complete bollock. Unless you do this as a day job or have lots of experience in building then you can't be expected to know this. Below are some of my thoughts.

 

1/ We are looking for a house that will meet the main functional requirements. These are; your kids, two have special needs and one not. You have grand parents. Their old hips are going to play up if not already! The we have you and your wife.. this needs to be a home for you also.. everyone!

 

2/ You have a budget and want to make it as well insulated as you can, with modern ASHP etc. But if you look at what of the old house is going to be exposed it's actually very little? It's much easier to add a bit to the odd old wall and then increase the insulation more in the new bits. This is often the most cost effective and pragmatic way. 

 

What to do as a next step, even if to rule out and check you are making the right fundamental and financial choices given that you are learning as the design develops:

 

My intention here is not to be patronising. I do this as a day job and can tell you that designs evolve as we gather more information and understand more about the constraints.. but in doing so often new ideas, stuff we have not thought about before comes into play. We in the day job get to change our minds often!

 

A: Nuclear option. What about demolishing the house down to the foundations? That way you can probably save 20% vat. You get to start with a blank canvass internally, recreate the outside, make the structure simpler? I look at what you are trying to do and just know that to retrofit what you want into a 1930's building likely not to going to be a pleasant journey for you. The labour element is going to be high.. so you pay for that and the stress that will come with it. 

 

B: Retain the existing external walls on the front / rear elevation, demolish the rest internally and rationalise the structural design and layout. This will allow you to reconfigure the inside layout and make it more buildable and that could well save you money and it may well be quicker to execute so you get into the house sooner. I would want to examine this option in detail.. 

 

Architectural observations: 

 

I'll now put you and your wife first. You are working hard, I bet every hour you have is a prisoner! I anticipate that the attic bedroom is your sanctuary.. it really needs a small ensuite. 

 

The ground floor stair case is too narrow at first glance. I can see how you have designed so far on the basis that you are trying to fit / add what you require.. then have some fun with the heating / solar and so on. Lots of people do this. 

 

To summarise:

 

If I was advising you I would choose this time to go back and review with you whether our internal design is still valid as per your post. I'm not saying you need to go back to planning. What I am saying is that I can see enough from what you have posted to warrant a comprehensive design review. I can see this from both an SE and from a designers point of view. I can see some scary costs from an SE point of view and even more scary when someone has to get the builder to do what you are paying for. 

 

I hope this helps.. even if you read my post and rule out.. it will, I hope, give you confidence. 

 

 

 

 

 

 

 

 

 

 

 

[JohnMo]

6 hours ago, fisnik said:

if it just enough so I can go for a heat-pump and not worry that it's going to cost me more than my current gas boiler in bills

Just a point worth thinking about.

 

Heat pumps the SCoP (annual measure of electricity in, to heating energy out) is directly proportional to flow temp. For a given house heat loss, a heat pump designed around a max flow of 55 degs compared to 35 degs will cost 75% more to run (SCoP are approx 3.85 and 5.10). So a low design temp will cost less than gas.

 

But sizing the heat pump correctly is really important.

 

As you can see, insulation isn't the important thing when installing a heat pump, correct design is. Gas or heat pump insulation and air tightness reduces the heat loss only - it doesn't make one better than the other. 

[fisnik]

Wow @Gus Potter. Thank you for the reply. All your feedback is much appreciated and of course none of it was patronising. 

 

You're right in that I hadn't thought about the steels. Although we considered that we may need quite a few and have spoken to our architect about hiring a structural engineer for the steel design we didn't think of the cost side of things. The aim was not to have any internal columns; I imagined that we may need a couple of square frames but perhaps I had that all wrong... 😔

The stairs are where the original stairs are so the design as such hasn't changed but they will be renewed. I'll post the existing drawings. 

I hadn't thought about demolishing all of it. I mean I would love to go brand new build if the cost was't much more.

Certainly, will consider what you're saying as we havent even spoken to an SE, just our architect. 

So much to think about. I will speak to the wife and mull over a few things. 

[fisnik]

1 hour ago, JohnMo said:

Just a point worth thinking about.

 

Heat pumps the SCoP (annual measure of electricity in, to heating energy out) is directly proportional to flow temp. For a given house heat loss, a heat pump designed around a max flow of 55 degs compared to 35 degs will cost 75% more to run (SCoP are approx 3.85 and 5.10). So a low design temp will cost less than gas.

 

But sizing the heat pump correctly is really important.

 

As you can see, insulation isn't the important thing when installing a heat pump, correct design is. Gas or heat pump insulation and air tightness reduces the heat loss only - it doesn't make one better than the other. 

Thanks. I am aware of that. My fear in terms of air to water heatpump is getting the heatloss survey correct given its a full renovation so can't use existing bills etc and also getting the design right. A Scop of 3.8 I would take with no problem.

Hoping a flow of 40-45 and mostly UFH downstairs will help with that.

I'm worried of having someone doing a botch job on it and get a Scop of 2.X and paying through the nose just to heat our home.

 

I would go air to air but we do use a lot of hot water. 

Edited 13 hours ago by fisnik

[JohnMo]

If you are going for heat pump grant, photograph and record every insulation and airtightness improvement you make. Many will ignore these improvements otherwise. Get an official air test at the end of works.

 

If you are doing UFH add at least 150mm of insulation (PIR) under and screed above or don't bother with UFH. A retrofit I would just do radiators, heat pump or PDHW boiler setup running Weather Compensation and/or room compensation. The boiler set up in PDHW will give almost instantaneously and endlessly available hot water.

 

Others on here, have similar age building and with upgrading some insulation aspects run radiators at 35, with boiler or heat pump.

[Nickfromwales]

10 hours ago, fisnik said:

I would go air to air but we do use a lot of hot water.

ASHP may not be the best for this, as there’s a lot of time taken to recover a cylinder fully, time where the heating isn’t serviced, as the heat pump will do one job at a time only.

 

Are you completely averse to staying on gas for 10-15 years? A gas boiler install would save a chunk of change and still isn’t a ‘hideous’ idea / route to take.

 

Depends on your priorities and aspirations I guess, and also if you have somewhere sympathetic to locate a heat pump?