Planning Our L Shaped Dormer Loft Conversion

When we started planning to have our loft conversion we quickly found out that having dormer loft conversions inflated the loft cost quite considerably compared to a Velux loft conversion – and having an L shaped dormer conversion with dormer windows inflated the cost even more. Home improvements are always expensive aren’t they?

But, an l shaped loft conversion was a design that worked well with our house and made the best use of the loft space rather than ending up with a really small loft conversion. So, it made sense to go all out and get the best loft conversion for us – an L shaped conversion. So we started working on the loft conversion design immediately.

Planning Our L Shaped Dormer Loft Conversion

When I started researching L shape dormer conversions it was really hard to find much information online or many L shaped dormer loft conversion ideas. There weren’t many suggested floorplans, home tour videos or even photos of finished l shaped loft conversions with an L shaped dormer. So I thought I would write about ours so it can help anyone else going down this route.

An L shaped dormer suits any house that is in an L shape and really makes use of all the available roof space. So if the back part of your house is smaller than the front, creating an L shaped roof, an L shaped dormer could be a good choice for you to maximise space.

The flat roof dormer creates square rooms from the pitched roof of the house, using flat roofs to give full head height and many more options when planning the layout of the loft conversion.

What do L Shaped Dormer Floor Plans look like?

This is the main outline of our loft conversion. We’re lucky that our stairs went straight above the original set, meaning we didn’t lose any space from our existing bedrooms to accommodate the stairs. This will vary massively from house to house.

Planning Our L Shaped Dormer Loft Conversion
The outline of our loft space

We could have had slightly bigger rear dormers if we had applied for full planning permission – but I doubt it would have been agreed – so we made the loft conversion slightly smaller to fit in with the local authority permitted development rights, so we didn’t need planning permission, which is based on the original roof size when the house was built. Back in 1904 in our case!

The extra space at the bottom of the floorplan could be used as eaves storage like the space in the roof void at the top of the floorplan.

With an L shaped dormer loft conversion there are a few options. The first option really is to create two distinct rooms. These could be two bedrooms, a bedroom and a home office or a bedroom and a bathroom. One would be in the main roof and one in the rear roof.

Planning Our L Shaped Dormer Loft Conversion
An l shaped conversion floor plan with two distinct rooms

If you’re happy to have smaller rooms you could have two rooms and a bathroom or en suite. There are a couple of layouts for this and the second one is pretty much how our plans started off.

Planning Our L Shaped Dormer Loft Conversion
L shaped conversion floor plans with two rooms and a shower room

This last design could also be split into an ensuite and walk in wardrobe to give you even more options if you wanted as well.

Our initial design started off as a main bedroom with a Juliet balcony – to increase natural light, a second room and a shower room. However, the more we looked at the plans the more we realised that the second room would be used for storage – it would have my dressing table and wardrobes in it rather than being a bedroom.

We realised we didn’t really need a fifth bedroom and would actually prefer a larger bathroom. So we changed the plans to have a large master bedroom, keeping the Juliet balcony. We made the shower room into a walk in wardrobe which would make more sense for storage and we turned the second room into a really good size family shower room.

Planning Our L Shaped Dormer Loft Conversion
L shaped conversion floor plan with a bedroom, shower room and walk in wardrobe.

It was important to us to make sure that the children, as they get older, or any guests, could use the new shower room without having to walk through our loft conversion bedroom which was why we didn’t have an en suite bathroom.

We also wanted to maximise as many storage options as possible given that we were losing the storage space that the old loft had provided. We chose to have built in wardrobes in the alcove in our bedroom, a cupboard in the shower room, a new boiler cupboard and a bookcase in the hallway as well as buying an ottoman bed for even more storage too!

Our L Shaped Dormer is perfect for our needs and the needs of our family as it grows. It has taken our home from a perfectly lovely three bedroom house to a two bathroom, four bedroom house that has space for me to work and that our family will be happy in for years to come. I cannot wait to show it off when it’s finished!

If you’re looking for more loft conversion help and inspiration, take a look at these posts:

Planning Our L Shaped Dormer Loft Conversion
Planning Our L Shaped Dormer Loft Conversion


  • Donna Wishart

    Donna Wishart is married to Dave and they have two children, Athena (12) and Troy (11). They live in Surrey with their two cats, Fred and George. Once a Bank Manager, Donna has been writing about everything from family finance to days out, travel and her favourite recipes since 2012. Donna is happiest either exploring somewhere new, with her camera in her hand and family by her side or snuggled up with a cat on her lap, reading a book and enjoying a nice cup of tea. She firmly believes that tea and cake can fix most things.

Similar Posts


  1. Thank you so much for this, it’s so helpful. I am looking at doing an L-shaped dormer and you are right there’s little on the internet. Lots of great tips, once again Thank You!! X

  2. Hi Donna. My wife and I are planning an L-shaped loft conversion, and found this article very helpful ! However I have a few questions regarding the rear part of the L-shaped dormer. From looking at the pictures, it looks as though your outrigger roof pitch is lower than your main roof pitch? And the rear part of the dormer roof is actually higher than the pitch of the outrigger roof. Is this the case? And if so, did you require Planning Permission, or did it come under Permitted Development? Ours is very similar, where the outrigger roof is lower than the main roof. I understand the conversion comes under Permitted Development is the roof is lower than the current roof height, but is this just applicable to the main/highest roof height?

    1. Hi Luke, thanks for the message and so pleased it was helpful. It all came under permitted development as all the constraints are based on the roof when the house was first built rather than any later additions. The outrigger part of our roof was added at a later date and so doesn’t factor into the permitted development rules. We decided to make the finished roof height the same across the whole house to maximise the ceiling height internally and we’re really glad we did. Hope that helps! Donna

  3. Hi Donna, this is really useful and has inspired us! 🙂

    I’d love to do something like a walk in wardrobe and bathroom combo, but not sure how plausible it would be with our space. I’m curious what the dimensions of that second room were which is now the bath / wardrobe combo?


Leave a Reply

Your email address will not be published. Required fields are marked *