Top 3 Garden Shed Extension Ideas

If you’ve found yourself thinking about shed extension ideas, it could be for various reasons. Maybe you want to add a workshop. Perhaps you need a greenhouse to protect your plants over winter. Or it could be that you would like to extend your shed to include space for leisure pursuits, maybe even a hot tub.

Sometimes, modifying an existing garden shed is the way to go. Especially if you have already invested heavily in your existing shed, it is of good quality and in excellent condition, and you would prefer not to replace it with a new one.

With this in mind, here are our top three garden shed extension ideas.

1.   Add a Lean-To

A dirt or wood floor lean-to has to be the simplest addition to a shed. Start by setting 10cmx10cm posts at the end of the shed, as far out as you want the lean-to to extend. You may need centre posts if the shed extension is particularly long. The outer posts should be set 25mm shorter than the shed side in order to create a drainage slope.

The next step is to attach 5x10cm rafter boards across the top of the posts along the length of the shed, and across the width from post to post.

If you wish, you can cut a door opening from the inside of the shed so that you can access the lean-to directly rather than just from the outside. You may also at this stage add wood flooring if you wish.

Next, add your siding. This could be plywood or wood planks. Just try to match the design of your shed, so that it looks consistent. If you wish, you can enclose the entire structure by adding siding to the end, or leave it open for easy access.

For the roof of the shed lean-to, nail plywood over the rafter boards from the shed wall to the outer beam. Be sure to add flashing under the shed siding and down the lean-to roof to keep it waterproof. Finish by laying down roofing paper and nailing on shingles.

2.   Add a Greenhouse

Another garden shed extension idea is to add a greenhouse. Mark out the plot for the greenhouse, and set posts in concrete at the corners and in the centre of the outside edge.

Now excavate the interior space to a depth of 20cm and frame it. Lay down 10cm of compacted grave, then pour 10cm of concrete floor. Level the concrete with a long board and smooth it with a trowel. This will form the base of your greenhouse.

Next, make a frame by adding top rails around the posts about half way up, and then add rafters across the width to hold the roof panels which can be nailed or glued in place.

For direct access to the greenhouse from the shed, cut a door and frame it with a header at the top to finish it off. Next, screw glass panels to the frame on all sides, and across the roof. Be sure to use rubber grommet screws so that moisture is sealed out. You could also use strong, clear plastic sheeting in place of the glass. Do be sure to seal the seams and edges with heavy duty tape, and use clear caulking to seal the greenhouse to the side of the shed.

Alternatively, you could buy a readymade greenhouse and place that on your base, connecting and sealing it to the shed in the same way.

3.   Extend your shed

If you simply want to make your shed bigger, you can extend it by removing one of the sides, extending the base and building new walls.

You’ll need to start by staking out a floor perimeter, and excavating to a depth of 20cm. Build a frame around it, then put down 10cm of compacted gravel before pouring 10cm of concrete. Level the concrete with a long board and smooth it with a trowel. This will form the base of your greenhouse.

Now you can build your walls, fastening the bottom plates to the floor with concrete nails or screws. The walls can be tied together with cap boards, overlapping the wall joints. The end walls and cap board need to be nailed to studs in the existing shed.

You’ll then need to add rafters across the extension which can go flat, wide side down.

Finish off by adding siding to match the rest of the shed. You can use some of the siding you removed if it’s still in good condition. Nail corner trim boards at the corners, and add flashing to the roof connection to waterproof it. This needs to go at least 10cm under the shingles on the existing shed roof, and 10cm down the new roof. The roofing for the shed extension should match the main shed for consistency.

Time for a new, bigger shed? Look to Surrey Hills Garden Buildings.

Not sure if you want to go to the trouble of adding your own shed extension? If you’re looking for a new, bigger garden shed, Surrey Hills Garden Buildings can help with everything from the planning to the design and installation, as well as the removal of your old shed.

Why not visit one of our dedicated show sites for inspiration on sheds and greenhouses? Our family run team is on hand to provide you with friendly, expert advice on all areas of shed design and installation.

Please do get in touch with any specific queries regarding sheds or shed door security. We look forward to speaking to you.