How to Insulate a Summer House

A summerhouse is designed with enough windows to keep warm in the summer sun, but can often be bitterly cold throughout the rest of the year. Like sheds, log cabins, and other garden rooms, there are a variety of options to insulate a summerhouse, including installing insulation in the floor, walls and roof.

For windows, heat retention can be increased through the installation of double glazing. All of this can help make your summerhouse a warm, usable space throughout the year, perfect for a garden office or gym.

How to Insulate a Summer House Roof

Before looking to insulate the roof of a summerhouse you should first check the status of its roof. The roof could be topped with a variety of materials, including felt, tiles, and EPDM. You should check the condition of any installed summerhouse roof, and if it is in a state of disrepair you will need to fix it in addition to installing insulation.

A poorly constructed roof will let heat escape and cause water ingress. Provided your summer house has a wooden roof, the best method to install insulation will be within the joists of the roof. You can cut PIR insulation boards to size and friction-fit them.

You will want to either install a breathable membrane against the roof before this or use an insulation product within an inbuilt breathable membrane, like foil-backed insulation boards.

You can then cover the underside of your roof with plywood or MDF boards, allowing you to decorate it however you see fit.

How to Insulate a Summer House Floor

There are two different ways to insulate a summerhouse floor, installing insulation above or below the floor. During the construction of a summerhouse, you’ll be able to install insulation under the floor easily. You can use solid insulation boards, fitted between the joists.

To ensure the boards stay in place you can either nail small pieces of wood to the joists, or you can use an expanding insulation foam around the boards. If your summerhouse has already been bought, then this method will require the summerhouse floor to be fully removed.

Depending on the age of your summerhouse and the condition of the floors, you should be able to dismantle and reinstall them, providing you carefully mark all components as you remove them.

An easier option for existing summerhouses is to make a false floor from insulation boards. This will lose you some height within your garden building, but will allow you to simply install thin insulating flooring boards, which can often be connected with tongue and groove joins.

This can then be topped with plywood or MDF boards, and decorated as you see fit.

Can You Insulate a Summer House's Walls?

Much like any building, there will be considerable heat loss through the walls of a summerhouse. Insulation can therefore be applied in much the same way as a roof, friction fitted between joists, with either a breathable membrane or a breathable insulation product used, and then topped with plywood or MDF.

As the joists within a summerhouse wall can be uneven, you should make sure to carefully check each gap before you cut the insulation to size. If your summer house is built with windows throughout, this can lower the value of wall insulation and make the process of installing it considerably more difficult.

In cases where your summerhouse is dominated by windows on three walls, insulating the walls may offer only minor benefits compared to double glazing. That being said, you can install some insulation around, over, and under any windows, and cover it with solid boards to improve heat retention.

Is it Worth Getting Double Glazing in Your Summer House?

Summerhouse windows can be upgraded to double glazing, which can greatly improve heat retention in buildings with many windows. There are a few considerations to take into account before adding double glazing to an existing summerhouse.

You should look at the current quality of your windows, checking for gaps around them. If you have draughts within the walls of your summerhouse you should seek to rectify these before installing double glazing, as gaps will cause heat to escape regardless of the thickness of your windows.

If your walls are in a solid condition, or if you are building a new summerhouse, then double glazing can be a great way to dramatically reduce heat loss. They will also reduce condensation within your shed, protecting it against dampness, and can offer acoustic insulation and improved security. Double-glazed summerhouse doors are also available.

How Much Will It Cost to Insulate a Summer House?

In most cases, summerhouse insulation can be installed as a DIY job, but it’s worth noting that if you’re looking to use a contractor this will come with its costs. Double glazing can be an expensive investment, with a 50cm2 window costing around £650, though there are sometimes deals for buying larger numbers of double-glazed windows in one go. See the latest costs of some of our insulation boards below.

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