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By Cara Mackay on 01 Jun 2020

What to look for when buying a shed – Shed Buying Guide

Buying a shed is no small investment so you’ll want to make sure it’s right for you and, more importantly, that it lasts. Buying a shed is not as simple as budget and size when it comes to longevity. There are quite a few things to consider to make sure you invest in your space wisely, you get your money’s worth and it looks goddamn beautiful in your garden.

Here we’ll only be guiding you through the best type of sheds: Timber sheds. You can learn more about different types of sheds right here.

Right now you should have a good idea of what you are using the shed for and how much space you have to work with. So what else do you need to consider? Here we’ll walk you through: 

  • Type of timber
  • Cladding Thickness
  • Framing
  • Type of cladding
  • Flooring
  • Roof type
  • Who’s making the shed?
  • Recommendations

Let’s get into some Sheducation!

Type of Timber

A lady came to me the other day who was checking out sheds because she needs a new one. She bought one two years ago and paid a fair bit of money for it, but what happened was that all the timber had shrunk, so there were massive gaps between the boarding in her shed.

That wasn’t the first time I’d heard this about that particular company, and so I explained to her that it’s very important to look at what type of timber that companies are using.

Redwood vs whitewood

We use Scandinavian pine, which is a redwood, which means that the timber is far denser than what the majority of other people tend to use, which is a whitewood, a spruce.

Redwood is dense because it grows in a slow-growing climate. Scotland is not the ideal climate, as we have far too much rain and sun, and the trees just shoot up. There is no consistency in Scottish timber. Its sporadic growth means that it breaks down dead easily. It cups, it splits and it shrinks very easily. And that’s where the problems occur when you are putting it into a shed.

Larch and Cedar

Larch and Cedar are very high-quality timber, beautiful but also expensive. Larch tends to be one and a half times the price of Scandinavian pine and Cedar four times the price. You’ll find a few limited shed companies provide this as an option because of the cost. We provide a Cedar and Larch option but customers prefer to use the option on much larger buildings such as Garages or Garden Rooms.

Beautiful G&M garden Room in Siberian Larch

When you’re on your shed search, definitely be looking for the type of timber the company is using. If they don’t provide you with that information, you’ll find that they are most likely using cheap whitewood. Companies usually tell you when they are using high-quality timber.

Cladding thickness

Cladding or timber thickness is everything when it comes to your shed. 

Type of cladding

Cladding is the exterior wall of a Shed.

The profile (shape) is vital to its ability to keep water out. If water is constantly penetrating your shed, it’s going to rot. 

There’s no guarantee that water won’t penetrate your shed. Wood likes to soak up water. But there are ways to avoid it as much as possible and it comes down to the construction of the shed and the materials used. 

The two main cladding options you’ll see on a shed are overlap and tongue and groove.

Overlap cladding

Overlap cladding is where the panels overlap one another. You’ll find that this cladding will result in a cheaper shed.

The challenge with overlap cladding is that it isn’t structurally stable to be able to hold anything on walls. So you won’t get shelving in this. Using this type of cladding with low-quality, thin whitewood is likely to result in a very flimsy shed.

Tongue and groove cladding

Tongue and Groove cladding are where the panels interlock like a jigsaw. This gives the shed a tight and smooth finish. There’s tongue and groove and weatherboard tongue and groove. Weatherboard has a slight curve in each board that aids the ease of water running off the shed. This is what we use at G&M.

Tongue and groove cladding is excellent for keeping the shed in shape over time. It’s strong, durable, and excellent at protecting against the elements. You’ll be able to add shelving and benches on the inside and hold heavy items on the walls. Don’t forget about the type and thickness of timber. The thicker the timber used, the stronger it’s going to be.

Tongue and groove sheds will cost more because the timber is clean dressed. This means the timber is dressed and gives a smooth finish. It’s the most costly type of timber but gives your shed that high-quality smooth finish.

Tongue and Groove Weatherboard

Note: Cladding is different from Interlocking Log:

Timber thickness

You’ll typically see thickness starting from 7mm up to 19mm for a shed. 

At G&M we use 19mm Scandanavian Redwood. We recommend that you don’t go below 12mm cladding thickness as that’s when issues can arise pretty quickly. 

At Gillies and Mackay Ltd we talk about sizes as the finished size.

For some reason, some manufacturers like to talk about sawmill size. This is completely pointless and misleading given you can’t add the sawdust back on to your Shed. 

Make sure you ask for the finished thickness. 

There are a number of reasons why thickness is important:

1. Longevity – Thicker timber will last longer with the right care – for example our bare timber has a life expectancy of 30 years. Every time you paint your shed, it increases the longevity of it. 

2. Sturdiness – The Shed construction relies massively on the thickness of cladding. Without it there is no structure to the walls allowing them to bow and sag. 

3. Weatherproof – Timber absorbs moisture – the thicker the cladding the harder it is to penetrate. 

4. Insulation – The thicker the cladding the more heat your building will retain. You can expect a G&M Shed not to drop below a 5 degree temperature, even in winter. 

5. Security – Plasterboard is 12.5mm thick and it doesn’t take much for an angry teenager to put their fist through it – so keep that in mind when it comes to considering how opportunists might take advantage of a thin shed.

6. Cost – The thicker the timber the more it’s going to cost. 

7. Appearance – Using dressed timbers will naturally look better in terms of knots and piths. Typically the higher the quality of timber the better it looks in finish. Makes for a good lookin’ shed people. 


It’s not just what’s on the outside that counts. Inside is important too. Framing is what is holding your shed together to make sure it doesn’t collapse, go lopsided, or blow away. The thickness of framing is important here.

On the market, you will usually find 45mm x 45mm framing. You don’t want to have anything less than this. We use 70 x 45mm framing which gives a very strong structure, bracing the cladding and maintaining a solid wall.  The bigger your shed, the thicker you should expect the framing to be. For example, the next size up at G&M is 95mm x 45mm, then 150mm x 45mm and so on. We’ll upgrade the framing depending on size. 

Inside a G&M Shed: 70x45mm framing

Pressure treated framing

Let us consider pressure treatment. This is a celcurised preservative that is forced into the timber grains and that protects the wood from rotting and insects for up to 40 years. The treatment causes the wood to have a slight green tinge to it.

This protection eliminates some common wood issues and framing is not where you want this to happen. It’s easy to replace a length of cladding on your shed if need be, but if the framing goes, so does your shed.

All of our Shed framing is celcurised.

pressure treated
Non Pressure treated vs pressure treated


Ah Flooring… It’s almost as if it doesn’t exist. A mythical creature typically left out of Shed manufacturers content, it’s as if they don’t want you to know what they’re using. Unless it’s actual flooring then what’s the point right? 

Flooring shouldn’t be any different from the cladding as far as I’m concerned. Make sure you get a proper answer about the flooring. Any chipboard or ply on an exposed floor is not okay – they are internal structural boards that don’t like the outside or being exposed to moisture. 

Shed roofing

What you need to know: – 

1. Coverings: – 

  • Felt 

It has a tar like material (polyflex)with slate flakes and comes in rolls. The weight indicates the durability and thickness of the felt.

Felted Roof on a G&M Shed
  • Steel Box Profile 

A thin metal sheeting, which has a plastic polyester coating sprayed on to it and is shaped like a castle turret – Steel isn’t cheap but does come with a 20 year guarantee.

Steel Box Profile on a G&M Shed
  • Bitumen Shingles 

Similar to Felt but made from bitumen. Shingles come in strips of 3 and are shaped to look like a slate roof, either square or honeycomb. Unlike felt which is laid on top, the shingles are bonded to the sarkin by their adhesive. They also overlap and cannot be used on less than 15 degree pitch. This means Shingles don’t leak unless they’ve not been fitted properly. 

Bitumen Shingles on a G&M Summerhouse
  • Sedum

A grass roof or green roof. Fairly complex and requires a strengthening of the trusses or purlins.

2. Make-up

  • Framing

The framing should be as the walls or bigger depending on building size. You would expect trusses in medium and large Apex sheds and that the framing in Pent sheds is spaced appropriately to withstand the weight.

  • Sarkin

Sarkin is the timber boards on top of the roof frame before the roof covering. 

  • Pitch

Apex is the A frame shaped roof as you would expect a Shed to look. The Pent is a mono pitched roof, ideal for going up against things. The Shaped roof is for angular buildings that are perhaps hexagonal and the roof meets in the middle. 

G&M Apex Sheds
G&M Potting Shed (Pent)

In the beginning

Traditionally Shed roofs are made up of lesser materials than the rest of the Shed; lighter frame, sarkin and some kind of cap sheet is what you’ll typically find on basic Sheds. Unfortunately, especially in Scotland, this isn’t good enough. 

A few years ago we were having a right problem with felt roofs on Pent sheds letting in water. What we were finding was that the felt itself was high in grade and weight, specifically sourced to last 15 years before needing replaced. 

However the roof pitch and size were massive countering factors which led us to our usual process of solution – take problem cases, test and try more excessive constructions, conclude on the result. In this case, Steel Box Profile was our solution.

All Pent our Sheds have a pitch of 9 degrees or less and have Steel Box Profile sheeting as standard on top of our tongue and groove sarkin – for sarkin, we typically use either flooring or weatherboard. Just like in the flooring example, we only want to see actual wood in the exposed roof. 

The reason I keep saying ‘exposed’ is because when the inside is the other side of the outside – it’s exposed. When the inside is separated from the outside layer by a cavity – it’s not exposed. Exposed elements need to be durable and weatherproofed – Chipboard is not for external use. 

You’d expect the framing in the roof to be the same size at least as the framing in the walls. In Apex roofs, you’d also expect the Truss frame to be bigger framing. A truss is an A frame which is fixed to the walls and joins the roof at the peak. 


Rafters and dwangs are what Pent roofs have instead of trusses. For small/medium sheds the rafters and dwangs will be the same as the wall framing. For bigger sheds over a wide gable you’d expect the rafters and dwangs to be bigger too.

rafters and dwangs

Our Apex Sheds vary between 15 and 27 degrees. Small Sheds can get away with just having felt, however, anything over a certain size or with a low pitch really could do with a Steel Box Profile. 


Because if the pitch isn’t steep enough the water will seep under the cap and if the roof is too long the felt will pull at the tacks and sag. 

Your shed roof has the sole purpose of protecting your shed, especially to allow the rain water to drain off. Keep weather resistance in mind at all times when thinking about roofing if you want your shed to last. 

Who’s making the shed?

Your options are mass-manufactured and bought in or hand-crafted from scratch. 

Mass manufacture sheds

Mass-manufacturing of sheds that are wholesale buy in are almost always the cheapest kind of shed you’ll get on the market. 

The challenge arises when you start to run into issues with your shed. It’s really hard to expect any level of aftercare with wholesale. 

You usually won’t get the option to alter the shed to your needs. It comes as it is. 

In most cases they are delivering them in a flat pack with self-assembly. But give the option for someone to assemble for you.

Places like B&Q, Wickes, Home Bargains, B&M Stores all sell Sheds that are typically from the same distributor often made in southern European countries and from very basic timber or timber substitutes.

You’ll typically find that they don’t give you the full spec and information you need to determine if the shed is going to last.

Companies like TGB sheds, Garden Building Centre, Dobbies etc have a more varied selection, some even have higher end English manufactured buildings from the likes of Crane and Malvern – These sheds are manufactured in bulk but are sometimes made with better materials.

Hand-crafted shed

Typically tend to be smaller businesses and they will be more expensive due to time, labour and materials. 

They will give you more options to alter your shed to your needs as they’re building it from scratch. 

Don’t forget to check out the types of materials used to make sure you are getting a decent build.

They’ll also offer some sort of guarantee or after-care service for your shed, that if you come into any issues they will be there to help you.

Independent Shed companies, like to offer delivery and assembly too, full package.

John Mackay – The Gaffer



When you are on your shed search, it’s always good practice to do a bit of digging on the company and see if they come recommended.

Check out their website and customer reviews in particular.

The best place to look is on Google reviews and their Facebook page.

Always take reviews with a pinch of salt – asking whether a review is genuine and/or if there’s more to it when it appears to be a complaint.


We’ve had customer’s, so dedicated in their research, that they’ve compared Companies House information, which was the deciding factor between choosing us over another company. That’s Sheducation!

You’ll find a bunch of reviews and comparisons on Scottish shed companies on our blog based on our shed knowledge.

There you have it Sheddie. These are the basic factors to help you along the way:

  • Type of timber
  • Cladding Thickness
  • Framing
  • Type of cladding
  • Flooring
  • Roof type
  • Who’s making the shed?
  • Recommendations

If you have any questions on your Shed search, we’re open to your questions and we’ll be sure to help you out. 

Email us at: info@gilliesandmackay.com

Good luck!

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