Commercial polytunnels: sizes, costs and choosing the right structure

 

The trolley fits through the doorway. Turning it is another matter: the first bed leaves your harvest wedged against the doorpost, with nowhere to go. Finding that out once the cover is on gets expensive.

A commercial polytunnel needs to fit your working day as well as your plot. When comparing commercial polytunnels, start with the crop and the equipment you’ll move through them. The advertised floor area comes later.

What size commercial polytunnel do you need?

Draw the beds before choosing the frame.

Picture an illustrative 8m by 20m tunnel, rather than a particular product. That’s 160m² on paper. Put in four beds, each 1.2m by 18m, and you have 86.4m² planted. Paths and room at the ends take some of the balance; the frame’s actual internal dimensions decide what fits.

How many trays does that leave room for? Count them on the bed drawing, because the footprint alone won’t tell you.

For commercial polytunnels, Northern Polytunnels offers single-span widths of 5m to 9m and multi-span widths of 8m to 12.5m. Before putting either on your drawing, get the supplier to explain where those measurements start and finish.

A bench fits on your plan for large polytunnels, then its outside edge meets the curved frame. Put its height on the drawing alongside the crop supports. Width at ground level doesn’t settle that question.

Single-span or multi-span structures?

One frame standing on its own is a single-span tunnel. With multi-span construction, adjoining bays become one connected growing space.

Do your crops need separate spaces, or does your day involve moving between them under cover?

With separate commercial polytunnels, one crop or production schedule has its own space. The site drawing also needs room for each entrance and the gaps between tunnels.

Moving equipment between connected bays keeps that journey under cover. But where does the trolley pass an internal post? Put the posts and gutters on the drawing before treating the growing space as an empty rectangle.

Neither arrangement wins on size alone. Compare the actual bed layout and movement routes in each proposed structure.

How much do commercial polytunnels cost?

Premier Polytunnels advertises kits starting at £1,642 for 16ft widths, £2,315 for 24ft widths and £3,326 for 30ft widths. These are illustrative advertised starting figures, with selected lengths unspecified here. They aren’t installed quotations or a like-for-like comparison.

The figure you need is the cost of your chosen structure, delivered and ready for your intended use.

Two quotes arrive with different totals. Does one include VAT and the other leave it out? Get that shown on both, alongside delivery and installation. Doors, ventilation equipment and foundation components need naming too. If ground preparation or irrigation sits outside the package, give each its own price line.

We can’t give you a sound installed total without the site details and a specification.

What about building it yourself? That removes a contractor’s installation charge, but you still need labour, suitable equipment and time away from growing. Paid installation suits buyers who need that work handled separately. Ask either way for a build programme in days, tied to your chosen size and site preparation.

If your present growing space meets demand, postponing the purchase is another option. Price the constraint you’re trying to solve before adding capacity.

Will access and ventilation work during a busy week?

An empty trolley rolls through. Loaded trays overhang both sides and catch the door frame. It’s the widest load you’ll move that needs measuring against the opening.

Then draw the turn inside.

In agricultural polytunnels, a bed that fills the drawing leaves no route for a trolley. Allow for the crop’s space and the paths, including turning room. Once planted, the tunnel also needs ventilation to control heat and humidity and keep air moving.

Who adjusts the vents while you’re elsewhere on the holding? Manual openings need someone there; powered controls add equipment and servicing costs.

With commercial polytunnels, the useful question is specific: how will air move through this planted layout with these doors and vents?

What anchoring does your site need?

Don’t order foundation components from a photograph.

The plot looks level, but part of it was excavated and filled. Tell the supplier about that made ground, alongside the ground conditions and exposure: the foundation specification has to suit what’s there.

A postcode leaves us guessing about anchoring. Before the quote arrives, establish who chooses the specification and what site information they need.

Compare quotations before placing an order

Send every supplier the same drawing. Your comparison checklist for commercial polytunnels should ask for:

•            The selected width and length, with clear internal dimensions.

•            Door openings and ventilation equipment, identified individually.

•            The proposed anchoring specification and required ground preparation.

•            An itemised price showing VAT, delivery, installation and exclusions.

A cheaper quotation deserves fair consideration. First establish whether it buys the same working space and equipment.

Today, mark out a bay with string and try the entrance with your loaded trolley. Record the measurements on one drawing for suppliers to price, so each quote starts with the layout you’ve tested.


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Choosing the best polytunnel covers for durability and UV protection

Are commercial polytunnels a good investment?