Rainhill, L35, sits in the St Helens borough and has semi-detached and detached houses from the inter-war years onwards, many with side or rear garages. Older garages here are often single-skin brick with piers and a flat roof, so a conversion usually means building a new insulated inner wall, upgrading the roof and laying a new insulated floor. St Helens Council is the authority for planning, and Building Regulations approval is normally required.
What do we usually find inside an older Rainhill garage?
Garages put up alongside inter-war and post-war houses were built to keep a car dry, nothing more. When we open the door on one, the same features tend to appear:
- Half-brick walls, stiffened by brick piers, with no cavity and no insulation.
- A concrete floor laid straight on the ground, often below the level of the house.
- A flat roof of felt on boards, or on older garages, cement sheets.
- A steel or timber up-and-over door in a wide opening, sometimes with a lintel that has seen better days.
None of that rules out a conversion. It just means the room is built inside the old shell rather than simply decorated.
Old cement roof sheets may contain asbestos. We do not disturb them. They need testing by a qualified surveyor and, if needed, removal by a suitably qualified asbestos contractor before any other work begins.
Bringing a single-skin garage up to standard
Single-leaf walls let rain through over time and lose heat quickly. LABC guidance says they need treating to make them weatherproof, often with a new insulated inner leaf or a framed inner wall with a cavity or membrane. Our garage wall insulation page compares the options. The figures LABC gives to meet or beat are:
| Element | U-value target (W/m²K) |
|---|---|
| Roof | 0.15 |
| External walls | 0.18 |
| Floor | 0.18 |
| Windows and doors | 1.4 |
The roof often needs the most work. A tired felt roof is usually rebuilt as an insulated warm-deck or cold-deck flat roof; see garage roof upgrade. Building control confirms the targets for each job.
Detached garages at the back of the plot
Some Rainhill houses have a detached garage reached down the side of the house. These convert well into a studio, gym or garden office, but they need everything: foundations checked, full insulation of walls, floor and roof, and new power, water or drainage runs across the garden. Planning matters too. The room should stay ancillary to the main house unless permission is granted for separate use. Our detached garage conversion page explains why.
Approvals in St Helens
Planning permission is often not needed for internal work that does not enlarge the house, but check your property’s planning history with St Helens Council before committing. For Building Regulations, a full plans application suits jobs with structural changes, because drawings are checked before work starts. Fees vary between councils and approvers, so confirm them directly.
Nearby areas we cover
Rainhill is next to Prescot, and we often work in Widnes and Halewood too. To see how we plan a conversion from start to finish, visit our garage conversion specialist homepage, which also covers converting garages throughout Liverpool.
Got an old garage in Rainhill?
Call 07777 659786. Tell us whether it is attached or detached and roughly how old the house is, and we will arrange a time to look at it.
Frequently asked questions
Is St Helens Council my planning authority in Rainhill?
Yes. Rainhill is in the St Helens borough, so planning questions, including whether permitted development rights apply to your house, go to St Helens Council. For building control you can use the council’s team or a Registered Building Control Approver. Rules can differ from neighbouring Knowsley, so check with St Helens directly.
Can I keep the brick piers in my garage wall?
Sometimes piers stay and are boxed in behind the new inner wall. If any are removed, LABC guidance says the single-skin wall is weakened and should be tied to a new inner leaf with remedial wall ties. That is structural work for qualified builders and is agreed with building control, never something to attempt yourself.
Can a detached garage in my garden become a bedroom for a family member?
It can often be used as an extra room linked to the household. If it is set up as a self-contained home with its own kitchen and living space, the Planning Portal says planning permission is usually needed. Council tax may also be affected, so check with St Helens Council and the Valuation Office Agency.
How warm can an old single-skin garage really get?
Once a new insulated inner leaf, an insulated floor and an upgraded roof are in place, the room is built to current Part L targets rather than garage standards. LABC guidance gives U-values to meet, such as 0.18 W/m²K for walls. Building control confirms what applies, and the result should feel like any other room in the house.