What Is BS 3632 And Why Should You Care?
Diane Cossie
Residential mobile homes are often at the start of a search for an annexe in the back garden and for good reason.
- They have modern open plan well designed living spaces.
- They come fully furnished (that’s carpets & flooring, tiles and wall coverings, blinds & curtains plus sofas, dining tables and lamp tables.)
- Some models have built in wardrobes, walk-in wardrobes, closets and utility rooms.
- They have fireplaces and fully equipped kitchens.
- En-suites to the master bedroom.
- Are available in 1,2 or 3 bedroom floor plans.
- Have modern tiled bathrooms and look and feel like a new home.

But what many of people will not know is that in November 2015 the current standard of mobile homes and leisure lodges was updated and upgraded with an emphasis on improved energy efficiency and reducing the environmental footprint of old style residential park homes.
The new standard brings modern residential mobile homes and leisure lodges (like our Caravan Act Annexes) to Residential Specification BS 3632 :2015 making them more than suitable for year round living.
These new energy efficient and well insulated buildings bear no resemblance to the out dated EN1647 standard that used to apply to Holiday Homes on Holiday Parks.
Just like today’s modern homes, today’s Residential Mobile Homes are every bit as good as what is often referred to as a “build on site annexe” but with the added perks of being able to be sited on your land with a Certificate of Lawfulness.

All annexes are classed as mobile homes
We’ve been at the fore-front of “evolution of annexes” in the UK over the last 8 years.
Since we started out at the Ideal Home Show back in 2011, we’ve been involved in supplying & installing annexes of all types ranging from Swedish Log Mobile homes which were imported from Sweden in kit form and provided a well insulated mobile home at a very competitive price.

We then saw the demand for “real little homes” increase as more people asked for traditional plaster-finish interior walls (instead of wood inside and out) and fully fitted kitchens and bespoke floor plans.
The build on site custom annexe is a service we still offer and it’s a very popular one with people looking to experience self-building on a smaller scale.
Gaining Planning approval will always be required for this type of annexe. You may also find that some Local Planning Authorities now have annexe policies in place which might reduce your desired specification and size.
Our success rate is very high and some compromises may be required for planning permission to be approved.
Everything our customers tend to love about this type of building is sometimes a concern for some Local Planning Authorities who may not consider the annexe to be ancillary to the main house if the size and specification is too big and too high.

For Example
A two bedroom annexe with a utility room, large master bedroom with en-suite and fully fitted kitchen might not be considered ancillary to the main house, especially if the main house is a 3 bedroom semi-detached property.
This has become more challenging for build on site annexes although we do maintain a high success rate as we work with your Local Planning Authority closely on your behalf as part of our turn-key service.
So what do we recommend as the best way to build an annexe?

Every garden and every annexe or lodge need is different.
70% or more are typically for elderly care of some kind, and should be granted Planning Permission without a hitch, although there are no guarantees we know from our extensive experience that if there are medical reasons why a member of your family needs special care an annexe is the most cost effective and best solution for all concerned.
With Care Home costs typically being £1,000 to £1500 per week or more in the UK right now a custom annexe or garden lodge will usually pay for itself in under 2 years.
The residential mobile home or garden lodge alternative

We’ve been in the annexe building industry for a good number of years and have a sixth sense when it comes to spotting trends.
With the amount of new homes being built in the UK today averaging 300,000 per year construction costs are increasing for both materials and labour.
So whereas the cost of a build on site annexe in the last few years was the most cost-effective way to build an annexe in your back garden; the new BS3632 standard mobile home annexes or garden lodges are now becoming increasingly popular for several key reasons:-
- If you are downsizing from a large home and want more space and amenities than a traditional garden annexe might allow.
- If you are on a single income, or are a single parent, divorcee or looking for a home of your own without living back at home with Mum and Dad.
- If you are a young person looking at alternatives to renting or buying what many people believe to be a new home at over inflated new home prices.
- If you are a parent of a millennial(s) and wondering how on earth you are ever going to help your children secure their first home.


We cordially invite you to take a fresh look at how residential mobile annexes or garden lodges look today
- They compare favourably on cost with custom build on site annexe when it comes to budget.
- They do not require planning permission but will require a Certificate of Lawfulness (commonly referred to as the Caravan Act) which we can apply for on your behalf.
- They are stunning – what more can we say! We can arrange a visit to a show model on request or you can request a virtual tour if you prefer.
- The timescales of manufacture are comparable with an on-site build time before you can move in.
- There will be minimal disruption to your garden or family life as you will not have a major construction project going on for 8 to 12 weeks. Siting and delivery is significantly reduced and completed in just a few days.
- These residential mobile homes are designed to be moveable at any time in the future.
- They also have a resale value potential if not required in the future (which your Local Planning Authority will love) and can help certain family circumstances with regards to some inheritance issues they may have.
- Visiting one will change your opinion on what is possible for you and your family for the better.

- Annexes win hands down as the most cost effective way to build extra accommodation in your back garden, whether it is for elderly care or as an affordable housing solution for a family member.
- The challenge will always be with obtaining Planning Permission for an on-site annexe build. Although our success rate is high, more Local Planning Authorites now have annexe policies in place than ever before that may dictate the final size and specification of your annexe more now than over the last few years.
- The most straight forward option for many medium to large size gardens is the stunning new ranges of Residential Mobile Home annexes designed like leisure lodges and manufactured to BS 3632 for maximum energy efficiency. These require a Certificate of Lawfulness which we will apply for on your behalf.
- Both are cost effective solutions for today’s challenging UK housing market, Care Home costs and renting for years to come.
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