Frequently Asked Questions
Aluminium and paint
Does aluminium suffer from condensation?
What are the advantages of aluminium over timber?
Can I have any colour I like? My windows are a Farrow & Ball colour and I want it to match.
How long is the paint finish guaranteed for?
We pass on the manufacturer’s guarantee of 10 years, but the science behind it predicts a lifetime in excess of 60 years. We have been coating our structures with polyester powder coating our structures since the late 1980s with no reports of the paint failing.
Does an Alitex greenhouse ever need re-painting?
How accurately are the doors, the glazing bars and corner joints finished?
We are the only greenhouse manufacturer to use CNC (computer numerically controlled) machinery to ensure the precision and accuracy of the profiles and sections we use. The latest technology, combined with an eye for traditional craftsmanship, produces an unrivalled level of finish.
What is the greenhouse made of?
Polyester powder coated aluminium. Before being painted, the aluminium sections undergo three pre-treatment stages:
- The cut aluminium sections get a hot soapy wash, then rinsed, and prepared with primer.
- The paint is then applied in powder form with a spray-gun which carries an electro-static charge so the paint adheres to the aluminium in a smooth, even layer.
- The painted sections are then passed through an oven, bonding the paint to the aluminium.
In order to control the quality, all our painting is done in house. Our quality is also monitored by an independent company every 6 months.
Wood and restoration
I’ve got an old original Victorian greenhouse. Can you restore it?
Unfortunately not, but we can replace it in aluminium. Before embarking on restoration, consider all the maintenance associated with a timber greenhouse.
NB: We don’t replace individual glazing bars or sections of timber greenhouses. All our sections are designed solely for use as an integral structure. A combination of wood and metal is not recommended, as the aluminium will remain sound, while timber section will continue to decay over time.
How well do the proportions of your greenhouse follow the design principles of a traditional timber greenhouse?
An eaves height lower than the top of the door combined with a steep pitch of roof not only provides a truly authentic appearance, but also optimises air circulation and light penetration to give the perfect growing environment. Cresting and finials on the roof are made of solid aluminium, die cast from their original timber counterparts to ensure both the shape and size are authentic and pleasing to the eye.
Do you make timber greenhouses?
No. Timber greenhouses have too many drawbacks. Typically they will need rubbing down and repainting every 2 years. Every 5 years, the putty holding the glass in dries out and will need replacing. Doors tend to absorb moisture and shrink and/or swell as the seasons change. Greenhouses are humid places in any case, so timber will quickly rot if left unpainted or untreated. Although cedar greenhouses don’t need painting, they will need treating.
Size and shape
Can I have double doors?
Yes. Generally the greenhouse will need to be at least 3.50m wide if they are to go in a gable end or about 8.0m long if they are for a lobby.
Can I have a lobby?
A lobby is a lovely feature that really captures the Victorian greenhouse look, but the dimensions have to be carefully assessed to achieve the right result. The minimum length to fit an extended lobby in a greenhouse is 5.10m. The minimum length for a flat fronted lobby is about 4.0m.
What happens when I am away?
We suggest the side vents are left slightly open. The roof vents will open and close throughout the day, so the greenhouse will remain vented.
Can you put Bayliss openers on the side vents so they open automatically?
No. Bayliss are designed to remain closed in colder weather and start to open at around 15°C (60°F). But, even in winter, you will need some ventilation in the greenhouse; hence the need for some manually operated vents.
Why do you only put vents in one vertical side and in one slope of the roof?
Will your greenhouse have the correct ventilation?
Ventilation is a critical part of growing under glass. Our combination of roof and side vents creates a 'chimney effect' inside the greenhouse that encourages air circulation and prevents unhelpful through drafts. The number of opening vents is designed according to the needs of each individual greenhouse to give the optimum level of ventilation. On larger greenhouses, vent depth can be increased accordingly and electric motors added for precision control.
Do you put in ventilation as standard?
Yes. Ventilation is such a critical part of growing under glass that we refuse to skimp on it!
Vents are positioned in one vertical side in a bank (or banks, depending on the size and shape of the greenhouse). They are 0.90m deep (3’) and operated manually using a traditionally styled solid cast aluminium lever and link system. The length of the bank(s) of side vents will depend on the length of the greenhouse.
Vents in the roof are also set in bank(s) and 0.610m (2’) deep. On greenhouses up to 3.50m wide they are operated by temperature sensitive openers. These consist of a piston filled with synthetic wax which expands, as the external temperature heats up, to open the vent. As the external temperature cools, the wax contracts and the vents close. Once set they can be left to operate automatically. The openers are often referred to by the manufacturer’s name “Bayliss”.
Greenhouses 4.50m wide will have roof vents 1.20m (4’) deep. Due to the increased weight of the vent, they will need to be operated by an electric motor.
Rear walls and lean-tos
Do you only build freestanding greenhouses?
No, we design many greenhouses to be built against walls.
NB: All greenhouses against walls are bespoke and are priced to take into account the additional design time needed. Our greenhouses in the National Trust Collection are all freestanding only. They cannot be adapted to fit against walls on any side. However, we can design a bespoke greenhouse of a similar size to fit against a wall.
To build a mono-pitch lean-to greenhouse around 3.0m wide, the wall will need to be about 3.50m high.
If the wall is not high enough for a mono-pitch lean-to, we can design the greenhouse as a ¾ span or even a “full span to wall”. A ¾ span will need a rear wall about 2.50m high.
The lowest height for a rear wall is 1.80m. The greenhouse will then be a “full span to wall”, i.e. the front and back roof slopes will be the same length, so the greenhouse will look more like a freestanding greenhouse pushed against a wall.
Bespoke greenhouses can also be designed to attach to a wall on the gable end(s) as well as on the rear.
Do you build greenhouses with glass to ground or do they all need to go on brick walls?
It is sometimes assumed the plinth wall will reduce light levels that plants, such as tomatoes, need. However, most light will enter the greenhouse through the long slope of the roof rather than the vertical sides. Plants on the rear of the greenhouse will get plenty of light at ground level as a result. Plants at the front will typically be on top of a bench above the height of the plinth wall.
We recommend a brick plinth 675mm high as this provides protection against frost and is typical of the Victorian greenhouse style. It also means items stored under the benching are hidden from view on the outside, so the greenhouse looks neat and tidy.
However, we can design a greenhouse to have a lower glass side, but it will still need to sit on 3 courses of brick and have foundations. This is because the attaching bolts are 150mm long and need to be anchored into solid material.
Polycarbonate gives better insulation do you ever use it instead of glass?
No. The aluminium glazing sections are not deep enough to accept sheets of polycarbonate. Also, polycarbonate scratches and dulls over time and detracts from the look of the greenhouse.
What kind of glass do you use and what happens if it breaks?
Will your greenhouse have undergone rigorous structural testing to ensure its legacy for generations to come?
Does the warranty apply to the paint finish on your greenhouse?
What guarantee do you offer?
The structural integrity of the greenhouse is guaranteed for 25 years or the lifetime of the purchaser, whichever is the longer.
- Paint finish is guaranteed for 10 years
- Accessories, electrical items and moving parts are guaranteed for 1 year
- Bayliss are guaranteed for 2 years
- Building work (by Alitex) is guaranteed for 10 years.
My greenhouse is not Alitex. Can I buy some cresting to go on it?
What are the grids for?
On larger greenhouses, heating pipes are located in a channel under the grid which allows hot air to rise through the greenhouse, as well as acting as a walkway. In addition, you can spray the heating pipes to create humidity, or add water to the channel for the same reason. They are also an attractive walkway that adds to the period feel inside the greenhouse.
In smaller greenhouses they are used mainly for decorative purposes.
Do you supply collapsible/folding benching?
What material do you use on top of the bench?
Can you fit your shades onto my greenhouse?
Do I need planning permission for a greenhouse?
- The greenhouse is located on land at the front of the property
- The height of the greenhouse would exceed 4.0m for a dual pitch roof, 3.0m for any other roof. The height of the greenhouse would exceed 2.5m if located within 2.0m of a boundary
- The height of the eaves would exceed 2.5m
- More than 50% the area of land around the ‘original house’ would be covered by additions or other buildings
- In general if you live in a Conservation Area, Areas of Outstanding Natural Beauty, National Parks or the Broads, planning permission will be required. In these areas the maximum area to be covered by all outbuildings more than 20.0m from the house to be limited to 10msq. Greenhouses in these areas located at the side of the property will require planning permission
- Within the curtilage of a listed building, a greenhouse will require planning permission and, if built against a listed wall - listed building consent.
Costs and timings
What is your lead time?
Examples of work
Where can I see examples of your work?
Over the years, we have created some beautiful Victorian greenhouses. On our case studies page, you will find a range of projects from our National Trust Collection and bespoke greenhouses. These case studies are a fraction of what we have built, we hope that you will find inspiration for your project.
We also have a number of display structures at our premises in Hampshire and have also built several in Hampshire, Surrey and Sussex as well as the Channel Isles. We have customers nationwide so may well have a structure nearer to you. Please get in touch and we will let you know.
Arranging an Alitex visit
Why is a site visit useful?
Past Alitex clients have always found a home visit to be worthwhile as it helps shape thoughts and provides a solid understanding of possibilities (and limitations). To see the house and garden of a customer and to discuss their requirements allows us to give useful advice. If you would like to arrange a visit contact us on 01730 826900 or email@example.com.
How do I arrange a no obligation visit?
Help, I’m not sure what I need!
Don’t worry this is where our years of experience can help. Contact us and we will chat through your growing requirements and advise you on your various options. Often, a no obligation visit is a good starting point. If you would like to arrange a visit contact us on 01730 826900 or email us on firstname.lastname@example.org.
Can I arrange for Alitex to visit me?
Can I use my own builder for the greenhouse base?
Yes, we will provide you and your builder with a detailed ground plan and the building notes to ensure the base is constructed to the correct specification.