Putting a loft hatch in a ceiling

A good sized loft hatch is always useful to allow ready access to the roof space of a property. Loft hatches in older properties are small (being just the width between two rafters) or non-existent - pre 1900/20 there was often no need for access to the roof space so no provision was provided.

In the modern day, access to the roof space is needed to allow the installation of insulation, roof space often includes water tanks and the loft space offers useful storage for lightweight items.

Even if you don't wish to fit a loft ladder, having a reasonably sized hatch makes access that much easier when you do need to go up there.

A word of caution:

Prefabricated roof trusses must not be cut without consulting a structural engineer as every part will have been carefully calculated to give maximum strength for minimum timber. Cutting any part will destroy the integrity of the truss and could lead to a structural failure.

Traditional cut roofs also need some caution for the diy'er, unless a structural engineer has advised otherwise:-

  • Never cut a joist connected to a strut or hanger.
  • Never cut through two adjacent joists.
  • Never cut a strut, hanger, rafter, purlin, binder or collar.

Note: for the terms used, refer to our roof construction page.

Where necessary, any of these things can be done providing that the integrity of the roof is maintained, this may involve certain addition to the structure and a structural engineer will advise what is necessary.

Positioning the hatch

Within the roof space determine a suitable position where a hatch can be fitted, the hatch should be sized to take two adjacent gaps between joists, thus you need to cut out a section of one joist. The places where a hatch should not be fitted include:-

  • Where the middle joist has either a strut or hanger fitted.
  • Underneath a binder.
  • Underneath a low collar.

Note: for the terms used, refer to our roof construction page.

If you intend to fit a loft ladder, make sure that there is sufficient space to the side of the proposed position for the ladder to lay flat on top of the joists.

What you have

Original small loft hatch1. You probable already have a small loft hatch between two adjacent joists - see right.

Marking joist to be removed 2. Measure the width between the inside of the joists over two gaps, then add twice the width of the timber (typically 50mm - 2 inches) being used to form the new sides for the hatch - this is the length of the central joist which needs to be remove. Mark the length on the joist to be removed.

Fitting support timbers3. Position two pieces of timber (25x75mm - 1x3 inch) across the top of the joists beyond each end of the proposed opening and screw them to the 3 joists - these will help support the joist/ceiling while you are making the hatch.

Cutting out joist for loft hatch4. Carefully cut away the centre joist - note that this will be back from the required edge of the inside of the hatch on both sides of the hatch - if possible leave the ceiling in place until the frame work has be constructed. This will allow the underside of the new timbers to be positioned on to the top surface of the ceiling.

Putting in new side timbers5. Cut two pieces of rough sawn joist timber to form the two ends of the new hatch and fit these between the two joists across the sawn end of the middle one. If the ceiling is lath and plaster, you may need to remove bits of plaster from above/between the laths so that the new timbers sit down on the laths. Check that the timbers form a square by measuring diagonally - the distances need to be equal.

Fixing side timbers for enlarged loft hatch6. Secure the new timbers to the existing joists - in a new house, these will probably be nailed, however, where the ceiling has been finished and/or decorated, it may be wise to screw them in place to avoid possible damage ceiling resulting from excess hammering.

Remove ceiling7. Now that the frame is in place, attach the ceiling to the new timbers using appropriate screws or nails. Cut back the ceiling to the edges of the frame - to minimise damage to the ceiling it will help to do this from below with any saw cut going upwards.

Finished loft access8. Remove the two support timbers screwed to the joists in 3 above.                                                 

The basic hatch frame is now complete, refer to our other page for forming the casing around it and the hatch itself.