Frequently Asked Questions

A gothic arch has a slightly pointed peak that goes down into rolled shoulders. We use the Gothic Arch because it is stronger than a rounded roof, and it is more appropriate for all weather conditions, including extreme wind and snow loads.

Gothic Arches allow for proper strength against extreme weather at all times of the year.

Each ventilation option has its advantages and disadvantages and should be chosen based on your customized greenhouse and situation.

Using roof vents will get good convection, but it is an expensive product and can be prone to wind damage. Roll-up sides are inexpensive and can be controlled automatically, but you will lose your humidity as soon as you roll up the sides. Wind damage with roll-up sides is a concern and requires extra steps to prevent.

With forced air ventilation, you can easily “set it and forget it” (with proper controls), which is wind-resistant. (As a side note, if you don’t do your calculations correctly with forced air, your greenhouse can end up quite warm).

At BW Greenhouse, we believe that Allied Gatorshield is the best steel on the market. It has the highest yield numbers at 50,000psi and has a superior coating to both hot-dipped galvanized steel and Galvalume.

It is a rust- and corrosion-resistant product that, when compared to competitors, has repeatedly come out on top. It also has a zinc interior coating that provides the inside of the tube with maximum corrosion and rust protection, so it is protected inside and out.

• It delivers to all end-users a smooth, shiny appearance.
• It can be easily fabricated…with no deformation or flaking of the base material.
• It can be produced at whatever length is needed to meet your specific requirements.

There are several different heating options for your greenhouse, and choosing one is dependent on factors specific to your situation. Some possibilities include natural gas, biomass, propane, geothermal, solar hot water (Tigi Solar), under bench, and forced-air heating…

Forced air heating is inexpensive and easy to use.

At BW Greenhouse, posts need to be set in concrete because they are an integral part of the rigidity of your building, and they protect against uplift and lateral loads.

Generally, in the Northern hemisphere, greenhouses are positioned north/south. With our BW Greenhouse high-diffusion coverings, that positioning becomes less of an issue because of the light conditions inside the greenhouse. As a side note, greenhouses should always be positioned outside of shadows.

BW Greenhouse can only provide comfort that our products have been designed correctly by only selling engineered buildings.

If you’ve ever had an insurance claim against a failed building, you’re fully aware that the process can be prolonged over many years, and you may lose time, all of the product that’s in your greenhouse, and money.

At BW Greenhouse, we put more into the engineering process to give you peace of mind that the product you own is well-made and reliable.

At BW Greenhouse, we pride ourselves on our doors for several reasons. Our single sliding panel or double panel doors are strong and versatile. They are pre-assembled, with heavy aluminum extrusions and great rolling mechanisms. The door frames are made with our aluminum extrusion, which will hold poly, Dynaglas, or Thermaglas polycarbonate.

Polycarbonate is a synthetic resin that can be easily worked, molded, and thermoformed. Polycarbonate panels are engineered to be strong, tough and long lasting.

Polyethylene is a tough, light, moldable, and flexible synthetic resin available in sheets.  Polyethylene for greenhouses comes in a variety of grades.  BW Greenhouse uses UV stabilized material it ensures a long product life.  Polycarbonate panels are engineered to be robust, tough and long-lasting.

Both glass and polycarbonate are used to cover greenhouses. BW Greenhouse believes that polycarbonate outperforms glass. There are often breakage issues with glass, and the cost of replacing glass panels is high.

Polycarbonate is stronger and more resilient and resists damage better. The two companies we work with, Palram (polycarbonate) and Poly-Ag (polyethylene), are two world-class companies that have customized some of the formulations for BW Greenhouse. They supply us with a superior product to glass.

Arch: BW Greenhouse ‘Arch’ FAQs

An arch is a curved piece of structural steel that forms the primary shape of a Freestanding Greenhouse (also known as a Cold Frame Greenhouse or Hoop Greenhouse). The curvature of the arch dictates its wind and snow loading capacities. BW has optimized its arch curvatures to maximize interior growing room without compromising its wind and snow capabilities.

The shape of the steel tube also helps determine its strength. BW Greenhouse® does not use either round or oval arches as they are not, in our opinion, as structurally stable or strong as comparable square or rectangle arches. Arches are strongest if they stay in plane when under snow or wind loads. Square and rectangle arches naturally resist the torquing better under snow and wind loads.

In addition to the shape of the steel tube used (square or rectangle), one needs to pay attention to the gauge of the steel and its yield strength. Clients regularly tell us that our Greenhouses are the strongest on the market. BW uses Gatorshield Steel from Atkore (Allied) Steel. This steel has a minimum of a 50,000 lbs yield strength. By comparison, most hot-dipped steel has a yield strength of only 32 – 34,000 lbs.

The weather patterns globally have changed quite dramatically over the last few years. BW Greenhouse recognizes that building codes often are not changed for many decades, so relying on them alone to determine what design specifications to build to is taking an unnecessary risk. Storms are becoming stronger, more frequent and bringing more snow. In many regions, the one in a 50-year storm has become a one in a 10-year storm.

As a result, BW recently up-gauged the steel in its major structural components, because we realize that for many of our clients, their Greenhouses are a source of income. Losing a Greenhouse to weather means not only having to replace the Greenhouse but also having to replace the crop and equipment inside as well as forfeiting a year’s revenue on top of that. This is why we design the strongest Greenhouses on the market (our clients tell us this regularly).

Anchor: BW Greenhouse ‘Anchor’ FAQs

An anchor is a specially designed structural component used to hold a Greenhouse in place on a concrete foundation. These foundations could include a footing, pile footing, strip footing, or concrete blocks.

There are two different kinds: mechanical or chemical. BW has partnered up with Hilti Industries to provide our clients with Hilti TZ seismic anchors to ensure that the Greenhouse remains stable no matter the conditions. In instances where the anchor ends up to close to the end of concrete foundation, BW will specify the use of epoxy and treaded rod in order to ensure there is no fracturing of the concrete.

Baseboard: BW Greenhouse ‘Baseboard’ FAQs

An industry leading innovation from BW Greenhouse® is our galvanized steel baseboards. These baseboards are used at the bottom of our arches to provide additional rigidity to our structures and to provide a surface to seal the bottom of the Greenhouse to as well as to attach different components to including roll-up sides tubes.

Our clients tell us that our galvanized baseboards are one of the best options we offer. They are strong and greatly reduce the maintenance of the Greenhouse. Our use of steel baseboards means we no longer have any wood components in our structures, which allows us to offer one of the only Certified Organic compliant Greenhouses on the market.

Clip: BW Greenhouse ‘Clip’ FAQs

Clip is an aluminum extrusion that is used as a base to anchor polyethylene covering to a Greenhouse or on a roll-up side. Clip is used on round profiles of steel generally used as roll up side or purlins.

BW has custom designed this extrusion to make sure it is deep enough to put multiple layers of polyethylene or shade cloth in it.

Aluminum clip is far superior to formed steel bases as these bases can lose their shape over time and corrodes.

Cross tie: A cross tie is a horizontal piece of steel that connects two arches. This component keeps the two arches from moving separately, giving the arch additional strength. Cross ties can also be used to hang baskets or irrigation lines from.

BW uses cross ties in all of our Freestanding Greenhouses (also known as Hoop Greenhouses or Cold Frame Greenhouses).

Crank: BW Greenhouse ‘Crank’ FAQs

For BW, a crank is a self-locking mechanism used to roll up the sides of a Freestanding (Hoop or Cold Frame) Greenhouse. Our cranks use a 4:1 ratio to make them easier to operate even if the roll-up sides are several hundred feet long.

Coverings: Coverings are fairly self-explanatory – they are what Greenhouses are covered with.

There are generally three different kinds of coverings used on Greenhouses: polycarbonate, polyethylene and glass. (BW Greenhouse® does not use any glass in our Greenhouses, because we do not feel that the cost, weight, lack of light control and dangers associated with glass warrant its use).

Instead, we use both polycarbonate and polyethylene.

Our exclusive global partner for our polycarbonate is Palram Industries. (See our Partner page for more information on Palram). Polycarbonate is an amazing material. It comes in a number of different colours and profiles. Its ability to control light is dependent on the resins used as well as the coatings applied. One of the most exciting developments from Palram The science now used in coverings has dramatically changed Controlled Environment Growing. Yields and quality of product have marked improved using both polyethylene and polycarbonate coverings. Incredibly high levels of diffusion and light spectrum control.

BW Greenhouse ‘Cold Frame Greenhouse’ FAQs

A Cold Frame Greenhouse is a Freestanding or Hoop Greenhouse that is not heated. These Greenhouses generally have a smaller on-centre arch spacing needed for the additional snow carrying capabilities.

BW Greenhouse’s Cold Frame Greenhouses are considered by most of our clients to be the strongest on the market.

Curved Purlins: BW Greenhouse ‘Curved Purlins’ FAQs

Curved Purlins are pieces of steel that run horizontally attaching one arch to another. They are curved away from the poly.

End Wall: An end wall is a solid end to a Greenhouse that is made of either polyethylene or polycarbonate. An end wall can have a sliding door in it for easier access and additional ventilation.

Energy Curtain: BW Greenhouse ‘Energy Curtain’ FAQs

An energy curtain is a heavy shade system that can be deployed at night or in low temperature situations to reduce the amount of heat that is lost through the Greenhouse covering

Energy Truss: BW Greenhouse ‘Energy Truss’ FAQs

An energy truss is a horizontal truss used in GUTTER Greenhouses to add additional load carrying capabilities to the structure. Energy trusses are used to hang crops from, frame shading systems or energy curtains.

Flat Bottom Bracket: BW Greenhouse ‘Flat-bottom Bracket’ FAQs

Flat Bottom Brackets are steel posts welded to plate steel to be used to anchor a Greenhouse or Shelter to a concrete or steel foundation. When anchoring into concrete, BW GLOBAL provides Hilti TZ Seismic Mechanical Anchors for their holding power and ease of use.

FREESTANDING Greenhouse: BW Greenhouse ‘Freestanding Greenhouse’ FAQs

A Freestanding Greenhouse can also be known as a Hoop Greenhouse or Hoop House as well as a Cold Frame (when it has no external source of heat).

BW Freestanding Greenhouses can withstand tremendous snow and wind loads due to their arch curvature (GOTHIC) and shape (SQUARE and RECTANGLE rather than round or oval) and materials (Gatorshield steel with 55+ksi yields).

Freestanding Greenhouse tend to be more economical than GUTTER Greenhouses but can sometimes cost more from a labour and heating perspective than the contiguous space offered by a GUTTER Greenhouse.

Footing: BW Greenhouse ‘Footing’ FAQs

A footing is a concrete foundation designed to hold the vertical forces (both downwards and upwards) placed on a Greenhouse from wind and / or snow.

All BW Greenhouses and BW Shelters require concrete footings (either strip or pile). This is to protect them from wind uplift and to provide a moment connection for the arch that will add to its stability (strength).

BW GLOBAL specifies Hilti TZ seismic mechanical anchors.

Foundations: BW Greenhouse ‘Foundation’ FAQs

A foundation is a structural base that is used to hold the Greenhouse in place. These foundations are generally constructed out of concrete. The concrete can be formed into pile footings, strip footings or precast concrete blocks.

Contrary to common belief, ground posts pounded into soil are not sufficient to anchor a Greenhouse down. This method does not protect the Greenhouse from uplift and does not offer the arches much lateral support. Not anchoring your Greenhouse to concrete will invalidate the warranty.

GatorShield Steel: BW Greenhouse ‘GatorShield Steel’ FAQs

GatorShield® is a proprietary steel by Atkore (Allied) Steel that has a very high yield strength and is extremely corrosion resistant (100 hour salt spray).

BW uses this steel rather than Galvalume or other pre-galvanized steels, because of its physical properties and the fact we have found that the GatorShield coating is much better and does not discolour polyethylene coverings.

Ground Posts: BW Greenhouse ‘Ground Posts’ FAQs

Ground posts are sections of steel that are set into concrete and slide into the arches to hold the Greenhouse down.

Contrary to common belief, ground posts pounded into soil are not sufficient to anchor a Greenhouse down. This method does not protect the Greenhouse from uplift and does not offer the arches much lateral support. Not anchoring your Greenhouse to concrete will invalidate the warranty.

Gutter Greenhouse: BW Greenhouse ‘GUTTER Greenhouse’ FAQs

A GUTTER Greenhouse is a Greenhouse that has gutters running along the sides of a bay to collect water and to attached to another bay. A series of bays can be attached to each other to make a large contiguous growing area.

The advantages of a GUTTER Greenhouse is more efficient use of available ground for growing, more efficient heating and greater labour savings.

GUTTER Greenhouses are used by large commercial growers and by Retailers who want to increase their profits.

Header: BW Greenhouse ‘Header’ FAQs

A header is a piece of steel that goes across the top of a door to support the door track.

Hobby Greenhouse: BW Greenhouse ‘Hobby Greenhouse’ FAQs

A hobby Greenhouse is a Freestanding, Hoop or Cold Frame Greenhouse that is used by hobby growers. Generally, they are smaller in width (12’ or less).

Hoop Greenhouse: BW Greenhouse ‘Hoop Greenhouse’ FAQs

A hoop Greenhouse is simply a Freestanding or Cold Frame Greenhouse by a different name. It is characterized by having arches (or hoops) that go from the ground to the top of the Greenhouse.

Lock: BW Greenhouse ‘Lock’ FAQs

Clip is an aluminum extrusion that is used as a base to anchor polyethylene or shade covering to a Greenhouse.. Wire (or wiggle wire) is inserting into the profile to accomplish this. Lock is screwed into the flat edge of a square or rectangular shape of steel used in arches or baseboards.

BW has a custom designed extrusion that is deep enough to put multiple layers of polyethylene or shade cloth in it.

Aluminum lock is far superior to formed steel bases as these bases can lose their shape over time and corrode.

Lock is usually used on flat surfaces, such a square or rectangular structural steel tube.