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Is flat and apartment eco renovation easier?

Mid floor flats can be kept warm by adjacent flats, above, below and on both sides and then eco renovation is only needed on the exposed wall and windows and for improved heating, ventilation and lighting.

When we bought our top floor, corner flat in central London, there was more that needed doing to make it into a Superhome.  Was this easier than making a house into a Superhome?

Comparing house and flat renovation

Eco renovation - you'll need to think about neighbours when renovating an apartment in a block of flats

You’ll need to think about neighbours when renovating an apartment in a block of flats

In terms of eco renovation, there are several differences between houses and flats.  They share the same components but flats will have fewer elements needing treatment.

House – Ground floor, walls and roof may all be losing heat

Flat – Only one or two sides losing significant heat

A house has both a ground floor and a roof to lose heat, a flat one or other, or neither; a house has a minimum of two exposed sides (except old back-to-back houses) whereas a flat is most likely to have a maximum of two.  However flats, like houses, come in many different forms and we need to differentiate between purpose made blocks of flats and conversions of large houses into flats.

Tower blocks can be concrete framed or large panel construction and low rise can also be solid brick or even stone walled.  Conversions will be more similar to houses. This can lead to a different approach to eco renovation, namely external or internal wall insulation. Blocks of flats can be ideal for external insulation wrapping up all the flats, renovating the facade and avoiding cold bridging.

External insulation of houses if often not applicable for reasons of aesthetics, space or related issues, and internal insulation often plays a more important role. The financial benefits of scale for an owner eco converting a whole block of flats can be considerable compared with individual house renovation.

Size matters

New cornice mouldings

New cornice mouldings were installed to maintain the period charm

Size may be an important difference, it is often more at a premium in flats. This can be important when considering dry lining. We went for one of the best insulating materials, polyisocyanuate, to minimise  loss of space in the 65 square metre flat. But the very small shower room was too small to take any internal insulation. We make sure the extract fan runs a lot to reduce condensation.

Now recent innovations in insulating materials, such as Aerogel and vacuum panels could provide a better solution here. We did gain useful floor and cupboard space by replacing the old floor mounted boiler and hot water cylinder with a (wall mounted) combination boiler.

High rise issues

A negative aspect was being on the 7th floor above public roads. Scaffolding would have been needed to replace the single glazed windows. We had unfortunately not taken advantage when previously the block had been scaffolded to carry out external repairs and painting. So the solution was to install secondary glazing on these windows, which has worked very well, and to replace the two windows on the internal walkways with double glazing, argon filled with low e coatings.

The issue of cold bridging I think may be very common, particularly in older purpose made blocks. We have solid floors supported on the solid brick walls, external walkways and numerous chimneys passing through the flat (every flat had a chimney for every room!).

We have not taken any action to insulate against cold bridging but I am keeping an eye open for any mould growth, none so far. There is undoubtedly heat loss through these elements but the upside of the solid floors, internal walls and chimneys is the benefit of thermal mass to reduce possible overheating in summer.

Neighbour problems

Vapour sealed roof insulation

External roof insulation wasn’t an option so the ceiling was insulated and vapour sealed

The other aspect of flat renovation is having so many neighbours.  We have strict hours within which building work may be carried out and of course moving materials and waste from a top floor flat has to be approached carefully.

Insulating our part of the communal roof area was a particular problem.  It’s a flat roof, solid and we think uninsulated, but in a good weatherproof condition. Replacement was not on the cards, but laying waterproof insulation on top of the asphalt (an upside down roof) would have been a good energy solution. However it was not possible to insulate only our section of the roof, the freeholders would have had to cover the whole section including the flats around us, and this was not on.

We have gone for the unproven solution of drylining the ceiling throughout the flat, sealing it carefully against vapour penetration.  We will keep an eye on this also.

How about renewables?

Photovoltaics and solar water heating are becoming quite common in eco renovation but are difficult for individual flats.  Roofs are normally jointly owned and used so agreement would be needed to install PV or solar water panels and then pipe and cable runs are difficult for non top floor flats.

Where a block of flats is being refurbished together, jointly used renewables are a possibility but require close agreement from occupants on usage. Although I have seen some example projects we did not pursue it with our refurbishment.

Benefits of flat eco renovation

Our flat is now lovely and warm and the heating rarely comes on, the solutions chosen have transformed the flat.  Other benefits of converting a flat? Our neighbours are very interested and I think jealous, several visited us on open house days, so we met more of them and hopefully they will be inspired do eco renovations themselves one day.

© Simon Burton, author of Handbook of Sustainable Refurbishment
December 2012

Further information:
Visit Simon’s SuperHome for more at open days in September.

eco renovation - talk to homeowners