Frequently Asked Lean-to Shed Questions

by John Coupe

Lean-to Shed FAQ – I get asked a lot of questions about building a lean-to shed and so I have pulled together a lot of these onto one page for you to browse. Hopefully, you can find an answer to your question in amongst these.

If not please visit my Shed Questions page and ask away.

My only request before you do this is to take the time to submit several pictures and write a good summary your problem. I am keen to help but if I just get a one-liner saying - “I need some help with my shed roof!” it takes a lot longer to help you get to the root of the problem and find a solution.

I look forward to hearing from you if you don’t find an answer to your question below:

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Lean To Shed

by John Andrews

I have a predicament and hope that your vast shed knowledge can help. For years now my shed has been leaking like a colander all the wood is rotten and there are slugs on the walls, and I have had enough.

I have just got an uncle to donate some wood he had lying around and have decided that this is the year that I replace the roof.

BUT...the shed I have is not a shed.

Confused I hear you say, the shed is built on the end of my house with the kitchen window right above the flat useless roof so a nice apex is out of the question says the wife.

Is there any way that you can put guttering on the wall under the window and flash it in or does that only work if you have four sides to a shed?????????

Please help. You probably will need more info unless you've come across it before? thanks very much.

Kind Regards

John Andrews

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Help with flashing detail to brick wall
by: John - Admin

Hi John,

The way I understand it you have a flat roofed lean-to shed up against the rear wall of your house. You want to replace it with a similar (but better constructed) building.

The bit I am not quite clear on is how the kitchen window looks out above the shed roof (possibly your house is on a slope?)

Anyway if this is all being re-done from scratch you need to make sure that the flat roof is not flat! It should have a minimum slope of 1 in 60 away from the house and the water collected in a gutter at the lower edge of the roof away from the house.

Up against the house, which I am assuming is masonry, you will need to use a lead flashing which will come at least 150 mm up above the level of the roof.

The flashing has two functions:

• Firstly, it weatherproofs the junction between the house and the shed from driven rain flowing down the face of the house.

• Secondly, it protects the masonry from splashes of rainwater bouncing up from the shed roof. If the masonry gets wet and with freeze/thaw action it will deteriorate over-time.

If you would like to send me a picture of the shed location, I will send you a typical detail of how to flash a flat roof into a brick structure.

I hope this helps.



Thanks for your help
by: Anonymous

Thanks John,

I will send you a picture of my dilemma when I have a moment. Yes I am on a hill and my garden is 7 to 10 feet below the floor level in my house. We have to go down steps to get to the garden.

Will update you asap thanks.


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Lean to shed

by Michelle
(Wales uk)

Hi John, I want to put up a lean-to shed against the side wall of the house up to the boundary fence with our neighbour. The shed will not be going past the front of the house.

Is this allowed to be done with regard to building regulations?

Many thanks for any assistance.



Hi Michelle,

Thank you for your question.

The rules regarding what can and can’t be built as a storage shed on the grounds of a domestic house vary widely from country to country and in the US from State to State.

However, the general approach to ensure that what you are building is within the rules and won’t be required to be dismantled at a later date are similar wherever in the world you are.

To help you understand this process here's an overview of how the building control system works

The specific regulations will vary but by understanding how the process works you should be able to understand the process better when reading the rules that apply to where you are.

The rules that apply to building any development whether it is a domestic or commercial development are the planning rules. To get permission to build a structure of any house (from a factory to a bridge) the person wanting to initiate the building will need to submit plans/drawings to a local approval authority (often the town or city council).

The drawings should show what they intend to build and how it will fit into the existing neighbourhood. The local authority will then listen to local opinion and rule as to whether the project can go ahead.

Once planning permission has been achieved then the developer will create more detailed plans

These drawings and calculations that will prove how his project complies will all local building standards, laws and regulations. The developer needs to submit these to the local authority to get proof that the building is safe to occupy. The local authority will then issue some documentation proving that the building has Building Regulation approval and is in compliance with building standards. This certificate is often required when the building is sold, as evidence of the building's suitability to a potential purchaser.

When it comes to sheds and other ancillary buildings

There are so many and they are so insignificant in the grand scale of things that there are rules on structures that are classed as Permitted Development. Permitted Development is allowed so that the planning system does not get clogged up with small projects that don’t have much significance in the big picture. If your shed fits within the rules of a permitted development then you can just go ahead and build regardless without the time and expense of a planning application.

One thing to note is that even though your project is a permitted development it may still require Building Regulation approval if the permitted development rules say so.

The rules of what is a permitted development are what you are interested in

The rules of what is a permitted development vary from place to place and are also occasionally revised so I don’t offer the service of saying what is and what is not allowed.

In relation to sheds and permitted development specific point that will be referred to in the rules will be such things as the distance of the shed from the house, the area of the floor plan, the height to the ridge or the eaves.

In your case, the rule that you are concerned about is whether the shed can be built to the side of the house but not forward of the main building line.

There are two approaches to finding out if this is allowed

The first is to do a detailed reading of the rules and if you are certain that your building complies then to go ahead and build.

If you are not certain then I would prepare some outline plans and take them along to the council to show them what you propose to build.

When you do this their verbal assurance may be enough for you however written advice would be preferable in case there is a later dispute. In some areas, you can submit your plans and they will issue a certificate of lawful development.

The certificate of lawful development is cheaper than a full planning application and can be issued much more quickly. It proves that your structure is outside of the planning system and complies with the permitted development rules.

I have prepared some sample shed plans that show the sort of thing that would be suitable to submit to a council so that they could confirm if something is a permitted development or not.

I hope that you found this useful and also that your project can go ahead.

I look forward to seeing pictures once the project is complete. ;-)

All the best


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First time lean-to shed build - sealing query

by Iain

Firstly, great site - I am looking to build my first shed and have gleaned a lot of useful information and guidance from here.

Secondly, my question: I am considering my first build to be a lean-to sharing a wall with the house in order to make the most of the narrow piece of land to the side of my house. How do I ensure that I will successfully seal the shed to the house and not compromise the house or shed with regards to water tightness etc. As a side note, I intend to consult with my local council to fully understand any restrictions/guidelines associated with this (as has been discussed on other threads).

The shed will be a pent roof type and plan to seal the top edge against the house with overlapping flashing, my real area of unknown is the vertical joints where the walls join the house. Is it really as simple as filling the void with putty/sealant? I'm sure there is a more comprehensive method to do this and any advice would be gratefully received.

On a separate point, there will be very little space (circa 100mm) between the outer wall and the neighbouring property, should I be concerned regarding a damp atmosphere in this gap? My intent is to fit guttering to this side of the roof to collect rainwater running off the roof, but I imagine the air will be still a lot of the time and so may remain moist. NOTE: the wall on this side will be pre-treated with a long-term coating (TBC) so will not require access to re-apply whilst I am in the property - that's the plan at least!

Sorry for the wordy post. If you need more information please ask.

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Sealing around junction of lean to shed
by: John


Thank you for your detailed question.

The way that many ‘lean-to’ sheds are built is that they are a complete shed in themselves in that they have their own rear wall so that the shed is structurally independent of the main structure. The flashing that is installed along the roof /wall junction is to stop the rain that runs down the side of the house getting in the void between the two structures. So the vertical junctions where the two structures meet can indeed be sealed with putty/silicone sealant as you are just trying to stop any wind driven rain getting in this junction and causing damp problems.

The above solution of two separate structures would be the ideal situation where you require the inside of the shed to be as dry and draught free as possible. Many sheds are built without the roof flashing or side sealant when items such as garden tools and bikes that are fairly resilient are to be stored.

With this sort of situation you may have to cope with the occasional leak or retrofit some weather proofing as you discover the direction of the prevailing winds that blow rain into any weak spots.

With regard to the gap between your neighbours house and the side of the shed I think that it is something that he should be concerned about. Not so much due to general dampness in the air but what happens when there is very heavy rain and the gutter overflows, or the gutter gets blocked. At this point you will be discharging water on to his wall. Definitely something worth considering and discussing with him.

Best of luck with your project and please let me know how your project progresses.

All the best


Another lean to querie!
by: Dave

Sorry for reopening an old post but I have similar issues as the OP.

I have a 4.5foot gap between the rear of my house and the boundary so have elected a wooden frame in the gap and ship lapped the gable ends. I have boarded and sheeted the inside which sits against the boundary fence and have roofed and felted and then used a flash strip on the side of the house/ top of lean to roof. I used the bitumen primer supplied with the flash strip but there is a small amount of leakage down the wall of the house (I haven't boarded the inside yet so that I could see if the roof was watertight).

This is my first build so I may have missed something obvious but what is the best way of making this waterproof. Should I remove the flash strip and silicone the small cavity between the felt and the house wall then reflash? Or place a larger flash strip over the one I have fitted??

Also once waterproof should I put anything such as waterproof/breathable sheeting up against the batons before boarding the inside of the shed/lean to?

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10x4 shed off of stucco house

by Paul Tyner
(Oceanside, CA USA)

Hello John, I want to build a shed off of our house that is roughly 10'wide by 4'deep and will give us easy access to our 4 bicycles. I was thinking on each 4' end - we'll need a door and on half of the 10' section a sliding door giving us a 5ft wide slider. Make sense...?

It is on a newer concrete slab and I'd want to use that as the floor. What questions do you have?
Thank YOU for your assistance.

Paul Tyner

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10x4 bike shed
by: John - Admin

Hi Paul,
Thanks for asking your question. I think that the size of shed that you are proposing sounds fine. Having doors both ends should allow you to get the bikes in and out easily enough. My bike shed has a door at only one end and I manage to get the bikes in and out OK with a bit of juggling at times. The sliding door on the long side could be useful if you need to work under cover, but may prove to be an accessory too far.

The absolute correct way to weather proof the junction between the shed and the house would be to break out the stucco locally to allow installation of flashing to waterproof the junction. A local builder should be able to show you what works in you area. You may be able to omit the flashing (I did on my bike shed) if the wall is sheltered and does not receive driving rain.

I hope that this is some help, let me know how you get on or if you have more questions.

All the best


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Shed attached to house

by Colin
(Essex, UK)

I am considering building a garden office on the land to the side of my house it is the old driveway before it was fenced off and a driveway put out the front of the house. The area is approx 6m long x 4m deep at the widest point and 2.5m deep at the narrowest (it is a wedge-shaped plot of land)

I want to know if there are any regulations that say I cannot build on the land without planning permission and importantly can I make the house one wall of the shed?

The other side of the plot is my neighbour's boundary and he has a similar plot on his side of the boundary.

The front of my plot is fenced off from the driveway and not visible from the road. The shed (office) will not be nearer the road than the existing house and will be under 2.5M tall

I am enquiring about the 5M rule (must be 5M away from the house)that I have seen on some sites but is not mentioned on the government's interactive website for planning.

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Just call
by: GreenBoy

Ok - personally i hate calling the council - my local one doesnt like giving info over the phone and want you to write - and then they dont reply! but thats a different story

Any way i think the 5m rule was dropped in the last revision because most modern houses dont have gardens large anough for you to comply with this any more.

here are the planning regs - hope they help

Planning Permission

Under new regulations that came into effect on 1 October 2008 outbuildings are considered to be permitted development, not needing planning permission, subject to the following limits and conditions:

No outbuilding on land forward of a wall forming the principal elevation.
Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof.
Maximum height of 2.5 metres in the case of a building, enclosure or container within two metres of a boundary of the curtilage of the dwellinghouse.
No verandas, balconies or raised platforms.
No more than half the area of land around the "original house"* would be covered by additions or other buildings.
In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from house to be limited to 10 square metres.
On designated land* buildings, enclosures, containers and pools at the side of properties will require planning permission.
Within the curtilage of listed buildings any outbuilding will require planning permission.

*The term "original house" means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

*Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

Please note: the permitted development allowances described here apply to houses not flats, maisonettes or other buildings. View guidance on flats and maisonettes here.

Common projects: Outbuildings
Building Regulations

If you want to put up small detached buildings such as a garden shed or summerhouse in your garden, building regulations will not normally apply if the floor area of the building is less than 15 square metres.

If the floor area of the building is between 15 square metres and 30 square metres, you will not normally be required to apply for building regulations approval providing that the building is either at least one metre from any boundary or it is constructed of substantially non-combustible materials.

In both cases, building regulations do not apply ONLY if the building does not contain any sleeping accommodation.

Lean to sheds and planning
by: John - Admin

The piece of legislation that you need to look at is the:
Statutory Instrument 2008 No. 2362.
The Town and Country Planning(General permitted Development)(Amendment)(No. 2)(England) Order 2008

This came in to force on 1st October 2008 and covers permitted development such as extensions and sheds. Greenboy is right in that there is no current mention of a 5m distance from the dwelling. However I have to be careful when giving advice like this as we have no idea of your exact situation. The document listed above covers several types of permitted development including house extensions and sheds.

If the proposed office is attached to the house it could be considered an extension and if you already have an extension up to the limits laid down in the above document it would not be permitted and could therefore limit any future plans that you have to extend.

If there is a question like this I think that it is always prudent to write in to the council to make sure that you are looking at things correctly.

In my day job as a structural engineer we often get calls from potential clients that had a cheap loft conversion several years ago without applying for building regs. They call because they are about to sell the house and a surveyor has spotted that they do not have the required building regs certificates. Because the job has been done on the cheap 95% of the time the work does not pass and they are faced with a stressful situation just at the time they are about to sell the house.

I don't go in to much detail on planning regulations as this site is read by visitors from all over the world and the rules vary so much from place to place. (for example the above legislation only applies to England, not Scotland Wales or Northern Ireland). However, wherever you are the same general rules apply, speak to the local council (however distasteful you may find it!). It is far better to find out now the true situation than be faced with an order to dismantle your shed when you have just finished it or at some future unspecified point that will always be very inconvenient.

Hope this helps.



permitted development
by: peter wadey

Permitted development -outbuildings.

There is now no 5 metre rule. If an 'exempt' outbuilding is for example attached or linked by a porch to the main dwelling and provided it is totally separate there does not appear to be any regulation which does not permit this.

This can beneficial in providing additional day room and similar accommodation.

Any comment from a planning officer to rebut this?

by: Anonymous

I've just erected a summerhouse 6m x 4.2m x 2.5m high and the council are having a field day saying it as to be fire proofed,its 24 feet away from the house but only 300mm from the border, can anyone advise what I should do next as far as I was aware I did everything on the council web site.

attaching a shed
by: Anonymous

Wanted to know can sheds be attached to home with added foundation

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Creating a lean-to on to an existing Gambrel shed

by John Szesnat Sr.
( Altamont, NY)

I am wishing help with building a Lean-to off my existing shed the existing shed (Photo Attached) is 10'x10' and 10'7" high. Need help in designing and with the roof pitch. I would like the lean-to to be as wide 8 to 10 feet and high as possible This a first for building as was the shed. Please, any help would be appreciated.

Thank you for your time and effort in this matter.

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Creating Your Lean To Shed
by: John - Admin

Hi John,
Thanks for your question. In my opinion the governing factor of the height of your lean-to shed will be the eaves level of your current shed. The new roof will slope away from the shed. I would suggest a minimum roof slope of about 20 degrees. This will probably limit the width of the lean to as at some point you will have a problem with headroom.

To maximize headroom for the shed on your photo (thanks for providing this it really helps!) build on the downhill side of the shed. Other tips to maximize the headroom available would be to have a dirt floor or cast a concrete base. Using a base like this will give you a height advantage as the existing shed looks like it is built on skids.

The critical junction to pay attention to will be the junction between the existing shed and the new roof. Lead, zinc or copper flashing or PVC alternative should be used here to water proof this junction and stop any splashes or wind driven rain getting the cladding any wetter than normal.

Let me know how this sounds so far and then we can move on to the roof structure and supports.

All the best


by: Geppetto

How did your project come out?

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