Two-storey side extension on end of terrace

[Bob77]

Hello,

I'm looking for some advice on extending my end-of-terrace house in Hampshire. It's the only one in the terrace of six houses that hasn't been extended, and is on a corner plot with a fairly narrow bit of north-facing land to the side. See plan - it's no 48.

 

 

Ideally I would like to add a two-storey extension on the side to allow a larger kitchen and additional living space downstairs, and a fourth bedroom plus an ensuite to the existing main bedroom (bedroom 1 on plan) upstairs, plus a single storey extension along the rear similar to what the neighbouring properties have.

 

The house at the other end of the terrace was extended to the side and rear a long time ago (planning granted 1984), originally as a self-contained granny annexe which has subsequently been incorporated into the main house. So there is a precedent for a two-storey side extension here. The ground floor has been extended up to the front building line but the upper floor has a setback - see photo attached.

 

 

Unfortunately I don't have quite as much space to play with as the house at the other end did. The distance from the external house wall to the inside of the boundary wall is 3.6 metres at the front of the house, and 3.8 metres at the rear. Obviously I would like to use as much of this space as I can but I assume I would not be allowed to build closer than 1 metre to the boundary? That would mean adding a 2.6 metre wide extension which would mean maybe 2.3 metres of usable internal space, assuming the existing external wall is still in place. Assuming I would have to set back the upper story to mirror the house at the other end of the terrace that would be more space lost.

 

View of current situation:

 

Existing floorplans are attached. North is towards the top left corner of the plans. There's an open fireplace at the north end of the lounge (currently with a woodburner) and the chimney then rises diagonally, which is what the thick part of the wall indicates on the plan.

Apart from any advice on the best way to use the space and what sort of budget I might need, I am looking for thoughts on heating. The house is currently heated solely by electricity (apart from the woodburner), with a combination of storage heaters, electric radiators and electric underfloor heating in the kitchen and bathroom. Heating costs are very high for the size of the house. There is a mains gas supply but it has never been connected and used. I would like to do something greener than gas heating but not if the cost would be astronomical. I gather the RHI scheme could offset some of the upfront costs if I installed a renewable source of heating but I don't know whether this would be feasible with a 1960s house that is not terribly well insulated?

 

Downstairs:

 

Upstairs:

[Russell griffiths]

Have you thought of moving, if you added £100,000 to your current house price what could you buy, could you go a rung up the ladder, semidetached better road. 

You will spend £100,000 in the blink of an eye doing that work. 

[ProDave]

Your issue will be how close to your boundary the planners will accept.  The building line of the adjoining road will be an issue, you will be going in front of that.  On the plus side your tall garden wall already breaches the building line and blocks any visibility so there won't be a visibility issue.

 

Only by putting a planning application in will you find out for sure.

 

 

[Bob77]

33 minutes ago, Russell griffiths said:

Have you thought of moving, if you added £100,000 to your current house price what could you buy, could you go a rung up the ladder, semidetached better road. 

You will spend £100,000 in the blink of an eye doing that work. 

 

I have considered it but this is a very expensive part of the world to buy in. To trade up to the additional space I reckon I would be looking at paying at least £150k extra, maybe more once moving costs are factored in. A very bog standard four-bed semi can easily be £500k+ at this end of Hampshire.

 

The mid-terrace next door to me (3-bed with a small rear extension) sold for £325k a year ago. The extended four-bed at the other end of the terrace sold for £450k four years ago.

 

But the main reason for wanting to stay put is that I currently have a private mortgage agreement with family (having bought the house from them). If I moved I would have to go to a commercial lender with all that entails (and no guarantee of getting a loan, because a decent amount of my income comes from freelance work).

 

Obviously I am keeping my options open but it seems to me that I could get more space for the same money by extending than by moving, unless of course I sold up and moved to a cheaper part of the country - which I would like to do one day but probably not while the kids are at school.

Edited April 5, 2021 by Bob77

[pdf27]

• I think you're going to have problems with the layout given where the staircase is - you're going to lose a fair bit of room from one of the bedrooms (probably #1) if you want to add a side extension upstairs and the resulting shape might feel very awkward.
• It's worth thinking about what you could do on the ground floor only to get what you want - if you put a big kitchen/diner on the side as the extension (which as a single-storey may be able to go closer to the boundary) then you could convert the garage/WC/utility into a big bedroom and most of the existing kitchen space into a ground floor shower room plus a utility room.
• Maybe also worth looking at the feasibility of a loft conversion - because you'd continue the existing stairs upwards that's likely to be more space-efficient with the existing bedrooms than a side extension. Probably depends on how much headroom you have in the loft - looks like you're ~7m front to back with a 45° roof so with a decent sized dormer on the back that's probably a fairly good option.
• If you're already heating with electricity, you're a very good candidate for a heat pump. There are quite a few people who have self-installed on here and found it cheaper overall than getting a professional install and claiming the RHI. In your case more work would be required to install radiators, but that's true for any heating system and the only difference for a heat pump system is that the radiators need to be a bit bigger - double where you would otherwise have a single for instance. Insulation helps a lot - the better insulated the house the smaller and cheaper the heat pump you need is - but it isn't mandatory.

[Bob77]

1 hour ago, pdf27 said:

• I think you're going to have problems with the layout given where the staircase is - you're going to lose a fair bit of room from one of the bedrooms (probably #1) if you want to add a side extension upstairs and the resulting shape might feel very awkward.
• It's worth thinking about what you could do on the ground floor only to get what you want - if you put a big kitchen/diner on the side as the extension (which as a single-storey may be able to go closer to the boundary) then you could convert the garage/WC/utility into a big bedroom and most of the existing kitchen space into a ground floor shower room plus a utility room.
• Maybe also worth looking at the feasibility of a loft conversion - because you'd continue the existing stairs upwards that's likely to be more space-efficient with the existing bedrooms than a side extension. Probably depends on how much headroom you have in the loft - looks like you're ~7m front to back with a 45° roof so with a decent sized dormer on the back that's probably a fairly good option.
• If you're already heating with electricity, you're a very good candidate for a heat pump. There are quite a few people who have self-installed on here and found it cheaper overall than getting a professional install and claiming the RHI. In your case more work would be required to install radiators, but that's true for any heating system and the only difference for a heat pump system is that the radiators need to be a bit bigger - double where you would otherwise have a single for instance. Insulation helps a lot - the better insulated the house the smaller and cheaper the heat pump you need is - but it isn't mandatory.

 

Thanks, that's some useful food for thought. I agree about the upstairs layout. The only access really would be to steal some from the existing bedroom 1 and create a new access through where the airing cupboard is.

 

 I have had a look at the floor plans of the house at the other end and they did something similar to this, creating a new master bedroom in the whole extension upstairs - quick sketch plan but squashed in to what I could potentially fit in the space:

 

 

However their new side extension was wider (2.8m internal) whereas I wouldn't have that much width - 2.3 metres or so is no good for a double bedroom. So that wouldn't work!

Something like this could be an option - creating a single bedroom at the front, which would still be bigger than the existing third bedroom, with the remainder for an ensuite shower room in the existing main bedroom. Again just a quick sketch so sizes not to be taken too literally. This would require taking out more of the existing external wall of course.

 

 

I'd still need to find space for a hot water cylinder too if I got rid of the existing airing cupboard. Basically I think the problem is there might not be quite enough width to make the two storey idea worthwhile. Plus of course adding a fourth bedroom might not be possible if the local council want one parking space per bedroom, as I wouldn't get four cars out there even if I paved over every square inch! And of course the integral garage, as with most 1960s houses, is no good for a modern car so we have already converted most of that, leaving just enough space for bike storage etc.

 

@ProDave the extension at the other end of the terrace also comes forward of the building line, although as the road curves it is maybe less obvious than it would be at my end. I'm hoping that with the precedent set there they would have less grounds to complain, although I suppose they could argue that things have changed since 1984 when that extension was granted!

 

@pdf27 Interesting info about heat pumps - that is something I had been considering. If I did go down that route, is it worth combining solar PV (or solar thermal?) with a heat pump? Presumably the main demand for the heat pump would coincide with the lowest input from PV, but then a heat pump would use even a modest amount of solar generated power more efficiently than using it in other ways?

Edited April 5, 2021 by Bob77

[pdf27]

10 minutes ago, Bob77 said:

I'd still need to find space for a hot water cylinder too if I got rid of the existing airing cupboard. Basically I think the problem is there might not be quite enough width to make the two storey idea worthwhile. Plus of course adding a fourth bedroom might not be possible if the local council want one parking space per bedroom, as I wouldn't get four cars out there even if I paved over every square inch!

I would tend to agree with you - you're in a big enough plot to make it possible, but not big enough to make it actually worthwhile.

 

10 minutes ago, Bob77 said:

Interesting info about the heat pump - it's something I had been considering. If I did go down that route, is it worth combining solar PV (or solar thermal?) with a heat pump? Presumably the main demand for the heat pump would coincide with the lowest input from PV, but then a heat pump would use even a modest amount of solar generated power more efficiently than using it in other ways?

That's really two questions:

1. Solar thermal plus a heat pump doesn't work, particularly an air-source heat pump. If you have PV or are willing to switch to a time of use tariff and run the heat pump accordingly then the cost of hot water is very low indeed when the solar thermal would be generating it since the COP is very high (warm air) and wholesale electricity costs are low as there is a lot of other people's PV on the system. That means unless you have an unlimited budget or the solar thermal is a hobby for you, you're better off spending the money on something else.
2. PV + heat pump does work, but you're correct to note that the peak demand and peak supply really don't match. There are some impacts however:
   1. It's relatively easy to run the heat pump in summer to generate hot water when PV is available, and with a handful of exceptions (exporting it via Octopus Agile during the evening peak is actually worth rather a lot - bad time to self-consume) you want to use your own PV where you can. However, if you want to do anything more complex than running it off a time clock things get difficult and you're in the region of making up your own control system - that'll change, but nobody is really offering a suitable system yet.
   2. To give you some perspective on potential costs, I've been playing around with historical pricing data from 2020 for Octopus Agile for a very efficient new build which runs the heating when prices are cheap as much as possible. For that the electricity used by the heat pump costs about 6p/kWh on average and the electricity generated by the PV is worth about 9p/kWh on average. For me that's enough to make PV financially viable and a heat pump cheaper than gas, but your numbers will no doubt be different.
   3. If your import and export tariffs are with the same supplier, you can essentially save up summer PV and use it in winter. Not hugely efficient (you'll typically get paid something like 1/3 of what you would pay to import it), but better than nothing, particularly if you can use cheap night-rate electricity a lot in winter. Essentially you're buying 30 years of electricity up-front at a known rate whether or not you're able to use it yourself. If for instance you're doing a loft conversion and have scaffolding up anyway this can make financial sense since access can make up a surprising amount of the total cost.

[Bob77]

2 hours ago, pdf27 said:

• Maybe also worth looking at the feasibility of a loft conversion - because you'd continue the existing stairs upwards that's likely to be more space-efficient with the existing bedrooms than a side extension. Probably depends on how much headroom you have in the loft - looks like you're ~7m front to back with a 45° roof so with a decent sized dormer on the back that's probably a fairly good option.

 

Yes, this is another option. Any idea of the ballpark costs for a loft to bedroom conversion incorporating a bathroom? The internal dimensions of the entire footprint are about 7m x 6m. A bit of trawling the internet suggests that a dormer conversion of that size could be done for around £40k, does that sound plausible?

 

I would still want more space downstairs but that could feasibly be done with a single storey extension to the rear, perhaps extending out to the side. Doing both might well be too expensive though.

 

This would of course also mean that if the planners insisted on additional parking spaces one could be fitted down the side.

Edited April 5, 2021 by Bob77