Extension vs Loft Conversion

sirhan_sirhan · 15 September 2010 at 9:01AM

I wonder if someone might be able to advise me.

I am currently weighing up two properties, with the possibility of buying one of them.

One of the properties has existing planning permission for a loft conversion, and I am trying to establish whether there is a way of getting a rough cost for the conversion. The permission is for a floor of 4.5m x 8m, thus 36sq m in area. It would comprise of a double bedroom and ensuite, and incorporate two dormer windows on one side, with two velux windows on the other. The cost would need to include installation of a staircase with a 90 degree turn halfway up.

The other house that I am considering has a larger garden, and thus the possibility of extending out at the back as a number of neighbours have done. At present though there is no planning permission. I am aware of the rough rule of thumb that extensions cost in the region of £1k per square metre, and thus a similar size area to the loft conversion would be roughly £36k.

Both houses are in the same town, in the southeast of England.

Any help with the calculations for the loft conversion would be useful, in order that I can compare this against the extension.

Thanks in advance.

Doozergirl · 15 September 2010 at 9:37AM

In the South East you would be very lucky to acheive £100 a square metre if you employed a builder. You would be looking more at £1300 and upwards depending on spec.

A loft conversion is cheaper than building a brand new extension, metre for metre but whether it adds as much value depends on the house. Three storeys can be unbalanced and don't usually sell for as much as a house of the same size but on two storeys.

Swings and roundabouts.

sirhan_sirhan · 15 September 2010 at 11:00AM

Many thanks for the reply Doozergirl. Taking on board your advice regarding building costs in the southeast, I could potentially be looking at closer to £50k. Given what I know about local house prices though, this would likely add around 120k onto the value of the property.

What I need to weigh this up against is the cost of the loft conversion, and what this would add to the value of the property. I believe that the added value is in the region of £90k. Thus I would need to be able to get the conversion undertaken for £20k or less, in order to achieve the same net added value of £70k. Seems unlikely that I would get such a conversion done so cheaply I know, but any assistance with estimating the costs of this loft conversion would be much appreciated.

Thanks again.

andrewmp · 15 September 2010 at 11:04AM

sirhan_sirhan wrote: »

Many thanks for the reply Doozergirl. Taking on board your advice regarding building costs in the southeast, I could potentially be looking at closer to £50k. Given what I know about local house prices though, this would likely add around 120k onto the value of the property.

What I need to weigh this up against is the cost of the loft conversion, and what this would add to the value of the property. I believe that the added value is in the region of £90k. Thus I would need to be able to get the conversion undertaken for £20k or less, in order to achieve the same net added value of £70k. Seems unlikely that I would get such a conversion done so cheaply I know, but any assistance with estimating the costs of this loft conversion would be much appreciated.

Thanks again.

I very much doubt a loft conversion which costs 20k will add anything near £90k to the value of the house. People will do the sums like you and buy one without and spend the £20k if it was true.

sirhan_sirhan · 15 September 2010 at 11:09AM

I think you are quite right Andrewmp. What I am trying to establish though is how much it would cost, in order to understand what net value could be added. Thanks though.

sunshinetours · 15 September 2010 at 11:19AM

Presumably you need to compare the layout of the two houses. An extension to the rear of the property may add more living space and a loft conversion more bedroom space. What is required on each house to work for you (or is this a development rather than a home?)
Also the spec of the existing roof and access etc will certainly have a large bearing on how much a loft coversion will cost. Not all loft conversion siwll work out cheaper than adding a box on the back as such
You are also losing storage space by converting a loft but not with an extension.

Is a two story extension possible which would probably give you the greatest addition to a house in terms of useful space?
As Doozergril says be careful not to unbalance a house with proposed works as it will not add what you may hope if it turns out as a compromise.

sirhan_sirhan · 15 September 2010 at 12:05PM

Hi Sunshinetours, it is in fact a two storey extension that I would be considering for option 2.

As regards long term plans, I see this as a stepping stone towards where we eventually want to be. It will be a family home for a year or two, but added value is also fairly key to any decision. (Don’t want to get into a debate about house prices here – I acknowledge that prices are likely to drop by some degree or another, but view that the property that we subsequently move to will drop by a similar proportion).

There are many other factors to take into account, and you are right to ask the question of what is useful to us. Property one gives us all of the living space that we currently need, and probably all of the bedroom space too, but is not in our preferred location; property two on the other hand is in the perfect location, but is deficient in both living and bedroom space. Property 1 is a repo, property 2 is part of a divorce proceeding, and our impression is that one of the parties is reticent about selling. Hope this helps you to appreciate the dilemma!

Good question re the existing roof. The property is less than 10 years old, and there is sufficient space to add the staircase for accessing it, without having to move any internal walls etc.

Thanks again for the response.

pingu2209 · 15 September 2010 at 12:10PM

Of the two properties, I would consider area first. Even within a small village there are normally better streets than others so I would tend to pick the better location first.

Between a loft extension and a back extension, i would pick the back extension if there is enough garden at the back to accommodate it and still have a reasonably sized garden.

Loft extensions are okay but I believe better value lies in a standard extension

Doozergirl · 15 September 2010 at 6:15PM

sirhan_sirhan wrote: »

Good question re the existing roof. The property is less than 10 years old, and there is sufficient space to add the staircase for accessing it, without having to move any internal walls etc.

Thanks again for the response.

Modern trusses are the hardest to accommodate a conversion. They are most usually made differently to traditional trusses for economy and don't accommodate conversions.

Stick your head in the loft. If you can see quite lightweight trusses that criss-cross all over the place, the entire roof needs to come off and brand new attic trusses put in. That obviously costs a lot more than trying to convert an existing loft. You need attic trusses that already allow you to walk around with the correct head height at the centre and above any

It's impssible to calculate a loft conversion without knowing what is there currently; a loft conversion can be a complete roof rebuild or a different combination of certain adjustments and additions.

If you are considering buying specifically to add a loft conversion, I'd get an architect in to look at the roof before you buy - it's pretty complicated. Two storey extensions need PP as well. Better to get someone to look over both before you jump.

Nixer · 15 September 2010 at 6:44PM

No idea about value and cost, but a note on Velux windows in bedrooms. Our last house (rented) had a loft bedroom with Velux windows and it was pretty noisy in moderate to heavy rainfall. I often woke up in the night when it was raining and I never did get used to it. I don't know whether Velux windows are always like this or whether you can get external shuttering to muffle the noise or what. If the Velux windows are above the ensuite and you can shut the door it's probably not an issue.

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Extension vs Loft Conversion

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