Frequently Asked Questions


Are all your products made in the UK?


100% of our products are designed in the UK and cast in British foundries. Casting locally here in the UK is essential to ensure the quality of the product and enable castings to be produced without the huge delays so often associated with imported goods.

What BS standard are the products made to?


We use about 6 or 7 different foundries to make over 100 different products. Some foundries are small with only one or two employees, others much larger employing hundreds of people and operating to ISO 9001 principles.

Consequently the quality policy of each foundry is different which makes it impossible to standardised the manufacturing quality of each item. However we do ensure a degree of uniformity in all our products by adopting our own quality policy to ensure the goods meet the rigorous standards of our customers. Every product is inspected four times before being shipped ie. at the foundry, upon receipt at our warehouse, in the workshop and finally on packing which has kept returns by customers for quality issues down to 3 orders per 1000, a very respectable 0.3%. For more details on our quality programme please see here.

Do you have any vent grilles to replace the corroded one underneath doorway?


Yes, these are normally 3″ or 4″ high (75 or 100mm) and are available here.

I have a listed building, are your products suitable?


It is likely our products will be suitable for your listed building as they have been used in Buckingham Palace, the prime ministers house at Chequers, All Souls College Oxford and Cambridge University in the past with no problems. But this is no guarantee that they will be approved for use on every building or construction. To guarantee they are suitable for installation into your listed building you will need listed buildings consent and approval from your local authority conservation officer. To help you get this we’ve developed sympathetic conservation vents and heritage gratings and included some examples of the customers and buildings were they’ve been installed on the relevant web pages.

Remember that cast iron has been the material of choice, used for ventilation and drainage gratings since the reign of Henry VIII in castles, palaces and humble dwellings up to and including the present day. It is both pleasing to the eye and appropriate for listed buildings and affords an airflow rate of 50% – 75% more than the equivalent sized terracotta air vent.

Here are some of the UKs most sensitive buildings, all of which have installed one or more of our cast iron gratings during renovation work…….



Buckingham Palace

All_souls_college oxford

Can you cut a grating to a specific size?


We can supply square hole cast iron gratings cut to almost any size, see here.

Should I use bare metal or painted air bricks?


Our advice is to use the most authentic option, especially for use in listed buildings. So long as rust marks won’t stain the walls of the property, we would suggest using bare metal air bricks, if available, for installation in a red brick building. If the building is constructed of painted render, stone or light coloured bricks then painted bricks would be more suitable.

Can I use your drainage gratings for highways?


Not really. Although we show our grilles supporting the weight of a tractor or car, our gratings are predominantly for use on pavements and walkways and in areas of light traffic such as a private driveway. They do not meet the 40 tonne test load required for installation on UK public highways and have not been tested to BS standard for use on carriageways.

Which vents are used with plastic cavity wall sleeves?


The Windsor cast iron air brick is designed to fit in the outside walls of a property and into the cavity wall sleeves either, single, double or triple ducts. The single duct requires one air brick, the double has two interlocking air bricks and the triple has three interlocking air bricks on the outside of the property. It is supplied as ducting and cast iron Windsor air brick combined as item CAV3, CAV6 or CAV9 , either in painted black or bare metal. The internal vent can be a number of options but most suitably the DAY104 daisy grille for the single wall sleeve, the DAY107 for the double wall sleeve and a HER9 drilled for the triple wall sleeve.

Which vents fit the periscope ducting?


A Windsor cast iron air brick is designed to fit in the outside wall with the periscope vent going into the wall and down below the internal floor boards. It is supplied as ducting and cast iron Windsor air brick combined as item PER3, either in painted black or bare metal. There is no requirement for a vent internally as the periscope duct ends with a plastic integral grille.


Do you offer discounts to trade and what is your best price?


Order online for a discount of between 5%-15% depending on the size of the order, remembering to use the appropriate discount code before checking out. Discounts and codes are  as follows:-

Order value up to £2000 = 5% discount with code 5OFF

Order value £2001 – £4000 = 10% discount with code 10OFF

Order value £4001 – £10,000 = 15% discount with code 15OFF

Large orders over £10,000 must be made offline with payment via cheque or bank transfer. We can apply a discount of 15% to the proforma but customers must ask for it, we will not apply a discount automatically .

How many do you have in stock?


We’re the worlds largest cast iron gratings stockist so we keep plenty in stock.

It is however possible that we may run out, especially after we’ve received an unusually large order for one specific sized product or vent. To check availability of stock and receive an indication of delivery time, customers are recommended to email there requirements to

I only need one, do you accept small orders?


Yes definitely, although we’ve supplied pallets of air bricks to blue chip companies and large orders to trade, about 1/3rd of our orders come from individual home owners who often require just one vent (normally a conservation or heritage vent).

I shouldn't be charged vat, can you refund the tax?


If you live in the Channel Islands, you are an EU vat registered business or are carrying out restoration or new build in the UK you may not have to pay all or any VAT. If you have been charged vat on your online order and want a refund please ask for it. We will require your vat registration number and full business address for the EU vat refund or proof from HMRC that you qualify for a restoration or new build reduction.

What is the delivery charge?


We deliver to UK and the world, prices are here

Are your prices inclusive of VAT?


Vat will be added at 20% to the cost of the prices shown on the website and also on the delivery costs for all UK and EU customers.

If you live in the Channel Islands, you are an EU vat registered business or are carrying out restoration or new build in the UK you may not have to pay all or any VAT. If you have been charged vat on your online order and want a refund please ask for it. We will require your vat registration number and full business address for the EU vat refund or proof from HMRC that you qualify for a restoration or new build reduction.

How soon will I get my goods, can you deliver tomorrow?


Small orders, under 10 items, if ordered before 1pm Monday to Thursday will normally be delivered the following day. Orders placed on a Friday will be delivered the following Monday. Drilled, modified, made to measure and all long gratings may take longer.

What is your return policy?


As a private UK customer you are covered by the distance selling regulations and we’re happy to extend this cover for orders under £1000 to businesses. This policy isn’t applicable to products that have been modified in anyway, full details of our refund policy is here.


How do I fit an air brick?


We’re asked this so often, we’ve put together a guide here.

How do I support a long drainage grating?


See some examples here and see the cast iron bearers that support the gratings here.

Please note – price quoted for bearers is for one. If you require a pair, you will need to order two.

Here is a cross section of the bearers


Can I fit mesh or a flap to the Conservation vents?


Mesh or a flap can be fitted directly to the spigot at the back of the 4″ conservation vent. Mesh can also be fitted directly to the spigot at the back of the larger, 5″ vent although the 5″ flap will need a spacer or short length of duct. This is because the flap fouls the sides of the vent when attached directly to the back of the 5″ spigot.

How to attach ducting


Can you paint air bricks in a particular RAL colour?


As Henry Ford once said about the Model T Ford “You can have it in any colour, so long as it’s RAL9005″ and that goes for our air bricks too (RAL9005 is black of course). Most are available in bare metal as an alternative which although they will rust, is an authentic finish for period property brick built houses of Victorian and Georgian age.

I am a specifier, where can I get the specifications of your products?


All the specifications for our products are shown here on the website under the relevant section. this includes free air flow rates, dimensions in mm and inches, thicknesses and weight of the item. If you can’t find the figures you are looking for or need specific free air flow rates, please contact us.

How many air bricks are required to ventilate beneath a floor?


An interesting question that crops up quite often and one that doesn’t really have a definitive answer. The reason for this is that the ventilation supplied beneath suspended wooden floors is “natural ventilation” and not forced or mechanical ventilation so it is variable and can’t be measured. The amount of air ventilating under the floor is not only dependant on the size of the vents and their number but also on a number of other factors, namely, position of the vents relative to the prevailing wind, amount of shelter surrounding the house, the elevation of the property and the air flow afforded through the sub floor ie. are all the vents on one side of the property or are there vents on the opposite side to allow a flow of air.

In Alan Olivers book “Dampness in Buildings” (BSP 1988) he suggests (page 115) 3000mm2 per metre of external wall spread at 1.5 metre intervals. This seems a reasonable assumption allowing a corresponding “outlet” of air flow at the back of the property also.

What is essential though is that existing vent holes are clear of debris and not obscured in anyway and there is no debris underneath the floor and no sealed unventilated sections. Also check the existing vents are above the ground level and not partly obscured by raised pavements or patios , a common occurrence. Insufficient sub floor ventilation can lead to serious degradation of wooden floor boards, increase damp and moisture levels on the ground floor and also encourage dry rot – an extremely serious problem that is difficult to rectify.

What air flow do I need for my combustion appliance?


Speak to a gas safe registered plumber or architect who is familiar with the building regulations for ventilating combustion appliances and open fires. Once you have the free air flow required you can match a grating or vent to suit your requirements by checking the specifications on the appropriate webpage on this website. If you can’t find the correct air flow, email the details of the required vent (internal and/or external) and the free air flow required.

Can I put mesh behind air bricks?


It may be possible but if the mesh is trapped behind a mortared in air brick and can’t be cleaned then eventually the vent would stop venting – making the vent useless. Instead, fit a flyscreen air brick, available in 9×3, 9×6 or 9×9 inch as shown below which has a removable front so the mesh can be taken out from time to time for cleaning. Or maybe fit a drilled vent grille with a flyscreen mesh over the hole and trap the mesh between the vent and the wall/floor.


Can I connect round ducting and square ducting to any of your products?


Ducting is very much a modern invention, developed mainly from 1960s onwards. As such most of the plastic ducting isn’t designed to fit into imperial sized air bricks or engage at the back of any of our vent grilles (which are all imperial sizes). It is possible to utilise imperial air bricks of 9×3, 9×6 and 9×9 size with the rectangular ducting but it will need appropriately named “duct” tape to attach the air brick to the square and rectangular ducting. It is also possible to use our square imperial sized Heritage and slotted vents and also the round slotted vents with round ducting but the ducting will not engage in the vent grille as the grilles do not have spigots at the back so the duct will need to be set back slightly and suitably secured.

We do however have some vents especially designed to fit metric ducting, the Conservation vents (item CON4 and CON5) and the Windsor air bricks (WIN3, WIN6 and WIN9). The Conservation vents have spigots at the back that will fit the flexible 100mm and 125mm plastic ducting available on our website or they can be duct taped to solid round ducting. The Windsor air bricks can be engaged into the metric cavity wall sleeves as a single, double or triple vent and one will also fit into periscope vent. The Windsor air brick can also be duct taped to a rectangle to round adapter so the air brick can be used as an extractor outlet from round ducting.

Does adding mesh to a vent reduce the air flow?


Yes, it reduces the free air flow by 1/3.

What size vent should I use with 4, 5, and 6 inch (100, 125, 150mm) diameter ducting?


We have so many architects, builders and property owners ask this, that we’ve written a huge guide available here.

I have a cast iron grating/airbrick i would like a copy of, can you cast one
for me?


We do not have the capacity to cast bespoke vents, regardless of the quantity but we can cut to size similar in cast iron using square hole pattern grilles. These are available here

Can I use cast iron gratings to upgrade modern Aco drains?


See here for more information on channel gratings and drainage.


Where can I find the free air flow of gratings?


All the free air flow rates for our products are shown here on the website under the relevant section. If you can’t find the figures you are looking for please email us.

We do not test any of our vents for pressure drop, flow rates or efficiency ratings but customers are welcome to purchase our vents or air bricks and then submit them to BRE or a similar laboratory or test centre.

What are the specifications of the plastic ducting?


All the plastic ducting we supply is UK made by Rytons. Links to the spec sheets for our periscope ducting and cavity wall sleeves can be found here

If you have any queries that are not covered on our FAQ, then please feel free to contact us and we will be more than happy to assist you.