Getting the height right #
“How high should it be?” is one of the first questions we work through with every client, and it is one of the hardest to change once the building is up.
The short answer: high enough for what you want to do in it now and later, and no higher than your site, your budget and the rules allow. Height affects how the building looks, what it costs, what fits through the door and what you can do inside.
Here is how I walk clients through it.
1. Start with how it will look on your site #
Before we talk numbers, think about the look you are after when you drive in the gate. A building’s height is always judged against what is around it: your house, an existing shed, the lie of the land.
Adding on to an existing shed. Here the heights are critical, and they are all set from floor level. Your new concrete floor either matches the existing one or has a deliberate step up or down. If you want the roof lines to match, the new building takes the same height as the old one.
A standalone building. Ask yourself whether it will dwarf or overshadow your house simply by being taller. That may not worry you. If the shed floor sits lower than the house, or the shed is down in a valley, height is much less of an issue.
Where everything sits on the same level, it deserves some thought. The straight sides of a shed can look large and imposing next to a home.
2. Height costs more than the extra cladding #
The higher the building, the higher the price, and for two reasons.
The first is obvious: more materials. The second catches people out. Taller walls collect more wind, so there is more wind pressure on the whole structure.
To cope with that, the frames need to increase in size and depth and the foundations have to be beefed up. So an extra half metre is not just a bit more wall. It flows through the whole building.
3. What will you do inside, now and down the track? #
What is the shed for? That question needs to go deeper than today. It is not only what happens in there now, but what might need to happen in there in the future.
Three things drive internal height more than anything else:
- Car hoists. Is it a two-post or a four-post hoist? Where will it sit? What is the maximum height you want to lift a vehicle to?
- Mezzanine floors. Do you want one now, or do you want the provision to add one later?
- Pallets and racking. Do you need to stack pallets, or install some form of racking? How high does it need to go?
If any of these is on the cards, even as a maybe, we need to allow for it at the design stage.
4. Getting in and out: the door sets the minimum #
Most of our buildings have roller doors, a steel curtain that rolls up above the opening. That roll has to sit somewhere, so it must be added to the opening height to get the minimum wall height.
Take a campervan as an example:
| Item | Height |
| Campervan | 3.2 m |
| Roller door opening, with clearance and room for a taller van later | 3.6 m |
| Space above the opening for the door roll | 0.6 m |
| Bare minimum to the underside of the roof | 4.2 m |
So a 3.2 m vehicle quickly becomes a building over 4 m high. As you will see in section 8, that 4 m mark matters.
Roller doors are not the only option. Sliding doors and sectional doors can be installed with less headroom above the opening. Bear in mind that a sectional door travels horizontally back under the roof when it opens, so it takes up usable space inside the building.
Get the door height wrong and it’s costly. We’ve seen a large feed pad building, not one of ours, where nobody had allowed for the full height of the tractor cab. On the first day the tractor arrived, it couldn’t fit into the finished building.
5. Roof shape changes where the height is #
There are two typical roof shapes, and they put the height in different places.
| Gable | Monoslope (lean-to) | |
| Shape | Lower sides, with a ridge running along the middle | One high side, sloping down to one low side |
| Gutters | Normally one down each side | One, on the low side |
| Highest point | The centre of the building | Always along one side |
This matters for a car hoist. With a gable you can put the hoist in the centre, under the peak, and often get away with a lower average height across the building.
With a monoslope the best height is always at one side, which may not be where you want to lift vehicles.
The difference between the high side and the low side of a monoslope can also be more than people expect. Roof pitch can only come down to about 4 degrees if the roofing warranties are to stay valid. Over a 10 m wide building, even that gives a drop of around 0.7 m from one side to the other.
Increase the pitch to 10 degrees or more and the difference becomes much greater. You can end up with a 5 m side and a 3 m side, which looks a little odd to some people. It may be exactly the look you are after, but it does need consideration.
6. Mezzanine floors: do the sums early #
A mezzanine needs about 5.1 m at the lowest point of the building, and often closer to 5.5 m. The test is simple: can someone walk all the way to the low side upstairs without hitting their head?
Here is the typical allowance:
| Item | Height |
| Clearance under the mezzanine | 2.4 m |
| Depth of the mezzanine floor members | 0.3 m |
| Clearance on top of the mezzanine | 2.4 m |
| Minimum at the lowest point | 5.1 m |
That 5.1 m is clear height under the main beams, not just under the roofing. The beams come down into the space, so the building itself may need to be more like 5.5 m high.
7. Clear span: keeping all the height you pay for #
Steelspan typically supplies clear span portal frames, which run from one side of the building to the other with no internal bracing in the way.
Many sheds rely on two kinds of brace that eat into the space:
- Knee braces, which run at 45 degrees from the column up to the rafter (the beam that carries the roof).
- Apex braces, a beam across the top that triangulates the roof peak.
Both come down into the usable height of the building. They can limit what you do in there now, and certainly what you could do in future.
It matters at sale time too. A buyer wants to see a nice, big, clear building and all the things they could do in it.
8. Rules that cap your height #
Sometimes the limit has nothing to do with what you want the building to be. Three outside factors can cap it.
Height to boundary rules. Councils set these through their district plans, and they limit how tall you can build close to a boundary.
Covenants. These sit on your title, or across a whole subdivision. A developer carving up new lifestyle blocks might, for example, limit any shed to no more than 4 m high.
The building consent exemption. We are often asked about building without a consent on rural sites. The exemption for single-storey pole sheds and hay barns covers buildings up to 110 square metres, and it also limits height to 4 m above floor level.
That 4 m is measured to the highest part of the building, so on a gable it means the ridge, not the walls. The exemption carries other conditions as well, including distance from boundaries and roof span. MBIE sets them out in its guidance on pole sheds and hay barns, and our post on consent-exempt farm sheds covers them.
Remember the campervan in section 4? At 4.2 m it is already over the line, so it pays to know early which side of 4 m you are on.
Your height checklist #
Before you settle on a height, run through these:
- Is it joining an existing building, and do the floors and roof lines need to match?
- How will it sit beside the house: same level, lower, or out of sight?
- What is the tallest thing that has to get through the door, now and in future?
- Have you added the door roll above the opening?
- Is a car hoist, a mezzanine or racking a possibility, even later on?
- Gable or monoslope: where do you need the height?
- Are there council rules or covenants limiting height on your site?
- Are you relying on the consent exemption, and so on the 4 m limit?
Let’s talk it through #
Heights can be a minefield, especially if this is your first shed and you have never had to think about these things before. There’s no rule of thumb: the right height depends on your site, your doors and what you want to do in the building. I am more than happy to talk it through with you personally.
Call Patrick on 021 711 281 or email patrick@steelspan.co.nz.
Patrick Whiteman is the Director of Steelspan Limited and has 25+ years in the building industry.
