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How to Install a Skylight?

how to install a skylight


More and more homeowners are choosing to install skylights and take advantage of the many benefits they have to offer: more natural light, better ventilation, greater energy efficiency, adding a feeling of space to smaller rooms and creating a more aesthetically pleasing home as viewed from the outside. To help everyone who is interested in fitting a roof light in their home, we have put together this guide.

There are a number of different types of skylights from which to choose when you are planning a new installation. With this in mind, we recommend that you decide which type you want before you do any in-depth research on how to fit a skylight. Whether you choose a frameless flat glass skylight, pyramid skylight, dome skylight, walk on skylight or any other type of skylight, you can find our professional fitting advice in one of the sections below.

Before you get into the details of how to install a skylight that you intend to purchase, it is a good idea to focus on the 2 basic factors that will play the biggest part in your installation plans: size and location. Only once you know exactly where you would like your skylight to be positioned and how big you would like it to be can you start to plan the installation in detail. In the following sections, you will find some specific advice on fitting various different types of skylight in your home. Please note this page provides a high level summary on how to install different types of skylights, roof lights and roof lanterns. For more detailed skylight installation instructions and up to date fitting instructions, please see the individual product pages as these could change when the products are enhanced over time. When reviewing installation videos please ensure the correct video is reviewed as each product can come with different variations which could mean a slightly different installation method.


In this guide, we discuss the installation methods for the following skylights.

types of skylights

Installing a Frameless Flat Glass Skylight

install frameless glass rooflight

Download >> frameless flat glass fitting and measuring guide

If you appreciate the low-profile, minimalist style of frameless flat glass skylights, you will be pleased to learn that they are relatively easy to install. An experienced roofer or builder will have no problem installing a roof light of this type in a residential property.

  • Measuring the Opening – The very first thing you need to do is to measure the opening into which you wish to install a skylight, rooflight or roof lantern. We recommend allowing a 5 mm tolerance for all dimensions that you measure, in order to avoid unnecessary fitting issues.
  • Prepare Timber Kerb/Up-stand – The next task you will need to complete in your roof light installation process is the preparation of a timber kerb or up-stand, to which the insulated glass unit of the rooflight will be secured.
  • Apply Roof Covering to Side of Up-stand – A covering needs to be applied to the kerb or up-stand, in order to make it weatherproof.
  • Installing Stepped the Insulated Glass Unit (IGU) – Apply low modulus silicone sealant to the upper surface of the kerb/up-stand before placing the top pane of the rooflight on top of it. Pressure should be applied all around the overhang, to ensure the sealant is evenly spread. Now the bottom pane should be set in place, with the aluminium angle already fitted and bonded. The angle should be secured to the kerb/up-stand and structural silicone applied between the bottom surface of the angle and the bottom pane. Now both panes will be fully supported.

That’s the basic procedure you need to follow when completing a frameless flat roof light installation. For all other types of skylight that we discuss below, we are assuming that you have already measured the opening, built an up-stand and applied a weatherproof covering to the up-stand if applicable.

Installing a Framed Flat Glass Skylight

install framed flat glass rooflight

Download >> LAMI RL Flat Fixed Glass CAD

Download >> TB406 Datasheet Standard Flat Glass Rooflight

Download >> CAD Drawing

Download >> fitting Guide

If you decide that you would like to install a non-ventilated, framed flat glass skylight in your home, you should follow the instructions below:

  • Expanding foam tape should be applied to the inside of the up-stand onto which the skylight is to be installed.
  • A silicone sealant should be applied around the outside of the up-stand
  • The glass unit should now be placed squarely on the up-stand, with an even gap all the way around.
  • Using the supplied fasteners, the unit should now be secured to the up-stand. Before the fasteners are screwed into place, plastic packers should be used to fill the gap between the skylight frame and the up-stand.
  • Snap caps should now be fitted over each fastener, to prevent tampering.

If you arrived on this page after searching for ‘how to put in a skylight’ and you are planning to install a framed flat glass model, you now know roughly what needs to be done. You can find more detailed instructions on the product page for our frameless models.

Video guide: TB400 Fixed Vented Flat Glass Rooflight on builder’s upstand Flat Glass installation guide:

Video guide: TB400 Fixed Unvented Flat Glass Rooflight on builder’s upstand Flat Glass installation guide:

Video guide: TB400 Fixed Flat Glass Rooflight on PVC kerb Flat Glass installation guide:

Installing an Electric or Manual Glass Opening Skylight

install electric or manual rooflight

Download >> TB401 Installation

Downlaod >> TB402 Installation

Download >> Tami Opening Kerb Detail

As we mentioned earlier, if you are looking for detailed installation instructions it’s always best to wait until you have chosen a specific skylight: how to install your skylight correctly will depend on the model you select. For instance, if you decide to purchase one of our opening skylights, you will have a little more work to do if you go for the electric rather than the manual model. However, the installation procedure is actually very similar for both these models so if you want to know how to install a skylight window that opens and closes, the first few steps are the same for both models:

  • Carefully remove the skylight from its packaging, ensuring the hinged section is not locked to the frame and can be opened to an angle of 90°.
  • Apply compatible silicone sealant to the exterior edge of the up-stand then position the kerb squarely on the up-stand, with the hinges facing up the slope.
  • Fix the kerb to the up-stand, with the 125 mm fasteners supplied with your skylight.

If you are following instructions for how to put in a skylight roof window with an electric opening mechanism, you will now need to arrange for a qualified electrician to come and make the required electrical connections. Once this has been done, the unit can be wired up by following the included wiring diagram.

Finally, for both manual and electric opening skylights, the last step is to make sure that the unit is firmly connected to the frame and is locked in the closed position.

Video guide: TB402 Manual Opening Flat Glass Rooflight on PVC kerb Flat Glass installation guide:


Installing Korniche Roof Lanterns and Pyramid Skylights

Installing Korniche Roof Lanterns and Pyramid Skylights

Download >> Korniche Brochure

Download >> Korniche Install Guide

Download >> Korniche Survey & Measuring Guide

Download >> Korniche Technical Brochure

If you are going to be installing a roof lantern, the procedure, whilst still relatively easy, is a little more involved. This is because when fitting a roof lantern, some assembly is required.

  • Eaves Beams – First, slide the eaves beams together with corner brackets and use tie wraps to secure each corner temporarily.
  • Sealant - Apply sealant to the corner areas of the eaves beams, as indicated in the assembly instructions.
  • Spider Assembly – Assemble the spider as shown in the instructions, making sure to use the correct size bolts and tapered washers when securing hips to boss and when securing rafters.
  • Jack Rafters – If you are using jack rafters, they can be rotated into position and secured with the supplied bolts and tapered washers now.
  • Attaching Spider – Attach the spider to the eaves beams, tighten the bolts fully and remove the tie wraps from the corner brackets.
  • Fastening – At this stage of the roof lantern fitting, the spider and eaves assembly can be fastened down, using screws through the predrilled holes. Use packers under the eaves beams to support each screw and don’t forget to make sure the beams are properly sealed to the up-stand.
  • Glazing – All glass panes should be inserted into retainers, with spacings as shown in the instructions. They can then be installed by locating the top edge of each one and rotating it into position.
  • Fitting of Caps – Whether you are fitting a roof lantern on a flat roof or a pitched roof, the final stage involves the fitting of all top and end caps, to hide the fastenings and to make them more secure.

Even though the skylight instructions for fitting a roof lantern are longer and more involved than those for most other types of skylight or rooflight, a competent roofer or builder should still be able to complete all of the necessary installation work in under 1 hour.

Installing a Pitched Roof Skylight

installing a pitched rooflight

Download >> Fixing Instructions 1

Download >> Fixing Instructions 2

Download >> Fixing Instructions 3

Most people are searching for instructions on how to install a skylight on a flat roof but what if you want a skylight installation guide for pitched roof models? Just follow the steps below:

  • Up-stand – First, you will need to have a weathered up-stand built at the proposed location of your new skylight. This up-stand should be at least 150 mm high and have a pitch of 5° to 60°, to ensure efficient water drainage.
  • Gasket – Having made sure the up-stand is free of dirt and debris, you can remove the cover from the adhesive side of the gasket and lay each side carefully, with a mitre cut at the centre of each one.
  • Frame – The frame should be positioned on the up-stand so that it is spaced equally on each side. You then need to push down on the frame to ensure good contact with the gasket beneath.
  • Internal Angle Brackets – The final part of the roof light fitting process on a pitched roof is to secure each angle bracket to the bottom step of the carrier frame, from the inside.

Follow the detailed instructions that are supplied with your unit to ensure a successful installation.

Installing a Dome Skylight

how to install a dome rooflight

Download >> TB186 Installation Mardome Trade Sloping and Direct Fix

If you want to know how to fit a roof light with a polycarbonate dome, the process is as follows:

  • Apply silicone sealant to the outside edge of the up-stand.
  • For vented models, you now need to fix the kerb to the up-stand, with the 125 mm vented kerb fasteners. Make sure the kerb is square on the up-stand before fastening it in place.
  • Now you need to remove the dome from its packaging and put it squarely onto the vented kerb or up-stand.
  • Fix the dome securely in place, with the dome fasteners and fastener buttons (which are already fitted to the unit). Once the buttons are gripping the dome and will not spin when torque is applied by hand, the unit is secure.
  • Caps can now be fitted to all fasteners, ensuring the key-way is correctly aligned on each one.

If you order your new units from us, you will, of course, be provided with full instructions on how to install roof light models with domes.

Installing a Dome Manual Hinged Skylight

How to install a dome manual hinged rooflight

Download >> TB188 Installtion Mardome Trade Manual Opener

For those of you who want to know how to install a roof window with a polycarbonate dome that can be opened and closed manually, this is the basic procedure:

  • Remove the skylight from its packaging, making sure that the hinged frame is not locked and can be opened to 90°.
  • Apply silicone around the edge of the up-stand.
  • Place the kerb squarely on the up-stand (with the hinges facing up-slope) and fix it in place with the supplied fasteners.
  • Finally, check the hinged dome is securely fastened to the frame and lock it in the closed position.

Whether you came here to find out how to put a skylight in a metal roof or a tiled roof, the above steps cover what you need to know as far as manual hinged dome skylights are concerned.

Installing a Dome Electric Hinged Skylight

How to install an electric opening rooflight

Download >> TB189 Installtion Mardome Trade Powered Opening

If you are planning to install an electric hinged dome skylight, you can follow the same steps outlined above for the manual opening model. The only difference will be that, after you have fastened the kerb to the up-stand, you will then have to arrange for an electrician to make the necessary electrical connections. After that, the skylight can be wired up according to the provided diagram and you can proceed to the same last step as above: checking the dome is secured to the frame and locking it in the closed position.

Installing an Access Hatch Skylight

access hatch rooflight installation

Download >> Access Hatch Measuring CAD Drawing

Download >> Mardome standard fixed dome data sheet

Download >> TB188 Installation Mardome Trade and Ultra Manual Openers

The procedure to follow for an access hatch roof light installation is basically the same as for the electric and manual hinged dome skylights:

  • Unpack your new access hatch skylight and make sure the hinged frame is unlocked and capable of being opened to 90°.
  • Apply mastic or silicone around the edge of the up-stand.
  • Place the kerb squarely onto the up-stand, with the hinges facing up slope.
  • Secure the kerb to the up-stand with the 125 mm fasteners.
  • Make sure the dome is firmly attached to the frame and is locked in the closed position.

Again, you can find more detailed installation instructions on the individual product pages for these skylights. Assuming that you hire an experienced builder or roofing expert, it should be possible to complete the installation in under 1 hour.

Installing Wendland Skylights

how to install a wendland roof lantern

Download >> Roof Lantern Wendland Fitting Guide

As a type of roof lantern, Wendland skylights are straightforward to install and need to be assembled on site. They are quite easy to install if you hire a qualified roofer/builder.

  • Apply silicone to the outer perimeter of the up-stand/kerb.
  • Drill holes in up-stand to accept bolts for eaves beams.
  • Place the beams on the up-stand, slotting the bolts through each hole.
  • Seal all cut ends of eaves and fasten down using appropriate fixings. Apply silicone to corner joints.
  • Assemble the spider, connecting all rafters and other components as outlined in the accompanying instructions.
  • Attach glazing stops to rafters.
  • Seal glazing end profiles (underside) as illustrated in the instructions and peel back the protective tab of film on the glazing supports attached to the eaves.
  • Lower each glass unit into place, following the detailed glazing installation instructions carefully
  • The final step is the fitting of rafter and ridge top caps, along with weathering barriers if you have any central rafters between the hips. Once all covers and caps are securely in place, the installation is complete.

For full details of how to fit a roof window like a Wendland roof lantern, please see the illustrated instructions that come with your new unit.

Installing Walk on Skylights

install a walk on rooflight


In common with virtually all types of skylight, a builder’s up-stand is required for the installation of walk on skylights. Once the up-stand has been built and a weatherproof covering applied, you can proceed as follows:

  • Apply compatible silicone to the upper surface of the up-stand.
  • Place the top pane onto the up-stand and apply pressure all around the overhang to ensure the silicone is evenly spread.
  • The bottom pane should now be put in place, with the support trim fitted and bonded.
  • The aluminium angle or timber batten should now be fastened to the up-stand, with silicone applied in between the underside of the batten/angle and the bottom pane of the skylight.
  • Once any excess silicone has been wiped away, you can cover the trim with plasterboard.

The installation is now completed, with both panes properly supported. Your walk on skylights will, of course, be supplied with more detailed instructions on how to fit a skylight of this type.

Installing AOV Skylights

how to install an aov smoke vent rooflight

Download >> TB286 Installation Mardome Trade Smoke Vent

An automatic opening vent (AOV) skylights are designed to act as natural smoke and heat exhaust ventilators and are commonly installed in commercial premises as well as some residential properties. If you want to know how to install a skylight of this type in your roof, the procedure is similar to that employed in all other hatch-type skylight installations:

  • First, you need to apply a generous amount of silicone sealant to the outer edges of the up-stand, which we are assuming is already in place.
  • Place your smoke vent squarely on the up-stand.
  • Connect wires to a drill battery and make sure the vent opens to 90°.
  • Secure the kerb to the up-stand with the 125 mm fasteners.
  • Reverse the position of the wires to the drill battery, thereby closing the vent. However, leave a small gap so the cable can be pushed through for connection to the electrical system.
  • Hire a qualified electrician to make the necessary connections and wire your smoke vent as per the accompanying wiring diagram.

The installation of your new AOV skylight is now complete. As mentioned above, the installation procedure is broadly the same whatever type of hatch-style skylight you may be planning to buy.

Video guide: TB286 Smoke Vent Dome on PVC kerb Mardome Smoke Vent installation guide:

Video guide: TB286 Smoke Vent Dome on builder’s up-stand Mardome Smoke Vent installation guide:

Installing Modular Skylights

how to install a modular skylight

Download >> TB293 Installation Mardome Glass Link

Download >> TB294 Installation Mardome Glass Link (Single Module Edition)

Once you have taken all of the measurements you need and you’ve checked that your up-stand is completely flat across its span, you can use the following instructions on how to install a skylight window of a modular type:

  • Apply sealant to the topside edge of the up-stand. Aim for an even 10 mm bead around the entire perimeter.
  • Now apply a second bead, 35 mm in from the first one.
  • Position the modular unit squarely onto the up-stand.
  • Fix the unit to the up-stand with the supplied screws, spacers, washers and packers.

That’s a rough outline of what you will need to do when you are fitting a roof light of this type. If you are fitting a modular unit that opens and closes electrically, remember to be careful when placing the unit onto the up-stand as you will want to avoid crushing any of the cables. 

In Summary

As you will quickly discover, your very first task when researching how to put in a skylight is to decide exactly which type of skylight you would like to install. The best way to do this is to measure the space in question and then think about the benefits of skylights that most appeal to you. If you are interested in more ventilation, for instance, a skylight that opens and closes is an obvious choice. You should also consider the interior and exterior décor of your home: some models of skylight are more suitable for contemporary properties while others may look better in a period home.

If you would like us to help you choose the perfect skylight for your home or you would appreciate some more details on how to install a skylight window, don’t hesitate to contact us right now.

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