24. INTERNAL DOORS

IS THERE A DIFFERENCE BETWEEN INTERNAL AND EXTERNAL DOORS?

Usually external joinery needs to be durable enough to withstand weathering and temperature changes whereas internal doors have a much less stressful existence. Internal doors are frequently quite flimsy and may be constructed of cardboard, manmade woodpulp vaneers and even polystyrene glued together in sandwich panels. Some constructions may last a lifetime internally but would disintegrate rapidly in external applications. Some manufacturers (e.g. Hume, Corinthian) supply external joinery using sandwich construction which may have a life expectancy of 5 years but, as they rely entirely on glue rather than actual mechanical joints (e.g. mortice and tenon), they are not a substitute for real joinery made from real timber. Internal doors are typically 35mm thick whereas external joinery should be 40mm.

WHAT TYPE OF INTERNAL DOORS ARE AVAILABLE?

Joinery doors
These are doors from either solid timber or engineered timber made using similar construction to external joinery. Engineered construction refers to manufactured timber that typically uses finger jointed cores faced with veneers to resemble real natural timber. Joinery doors are more expensive than sandwich doors.

Sandwich Solid Cores
These doors may be faced with plywood, masonite or MDF over a solid core of laminated timber blockboard, MDF or particleboard or a timber surround frame filled with polystyrene or other sound deadening material. Solid core doors are typically half the price of joinery doors

Sandwich Hollow Core doors
Usually constructed using a cardboard honeycomb core within an edge strip frame faced with plywood, masonite or MDF which may be moulded or routed to a face pattern. These are the budget end of the door market. Hardware can only be fitted in specific locations where timber lockblocks have been installed to allow attachment of locks and handles.

stile & rail
construction

solid construction
core made from MDF faced with MDF moulded panels

coriTech core construction
MDF and polysryrene faced with MDF or tempered masonite

blokdoor designs
core made from laminated FJ softwood faced with plywood or tempered masonite

solidor designs
core made from high moisture resistant particle board

honeycomb core construction

DOES WOODWORKERS MANUFACTURE INTERNAL DOORS?

Woodworkers manufactures joinery doors and imports its own range of engineered doors for internal applications. We do not manufacture sandwich panel doors. We resell product from Corinthian, Humes and other suppliers to provide the widest selection to clients over the complete budget spectrum.

WHAT SIZE LIMITATIONS APPLY?

Stock doors are commonly available in 2340 and 2040mm heights and widths from 520mm to 920mm, although some ranges have far more constrictive sizes. The sizes you require may severely restrict your design choices. Most sandwich panel doors can be trimmed no more than 5mm from any edge. Where unusual sizes are needed a solid core blockboard door would be required or custom joinery ordered. Where very large doors are envisaged, the limitations of plywood become restrictive and necessitates joints to be generally displayed where the size exceeds 2400 high or 1200 wide.

HOW LONG DOES IT TAKE TO GET INTERNAL DOORS?

It is often assumed that internal doors are available off the shelf and ordering them is often left too late. While Woodworkers stocks its own range of internal doors ready for cash and carry, many designs and sizes need to be manufactured or transported from interstate. For designs from the Corinthian or Hume range a minimum of 12 working days should be allowed. Where doors need to be pre-hung or have other customising work carried out a further 5 working days is usually required. If joinery doors require manufacture, the lead times will depend on the factory backlog but will be the same as external joinery (commonly 3 to 6 weeks).

WHAT WARRANTIES AND SALE CONDITIONS APPLY TO INTERNAL DOORS?

All internal doors are warranted by their respective manufacturers for 5 years. A number of stringent sale conditions apply to many of the designs that are set by the manufacturers. These often entail the condition that orders can be changed on the day of ordering only. All internal door orders are not returnable unless the doors are defective. Check with our sales staff what conditions apply to the doors you may wish to order.

WHO INSTALLS INTERNAL DOORS AND HOW THEY SHOULD BE HUNG?

All internal doors are warranted by their respective manufacturers for 5 years. A number of stringent sale conditions apply to many of the designs that are set by the manufacturers. These often entail the condition that orders can be changed on the day of ordering only. All internal door orders are not returnable unless the doors are defective. Check with our sales staff what conditions apply to the doors you may wish to order.

WHAT FRAMES ARE USED WITH INTERNAL DOORS?

Unlike external joinery which requires sills and generally 140 x 32mm solid framing, internal doors usually only have 19mm thick 'reveals' lining the opening 3 sides. These may be builder supplied or ordered with the internal doors as a pre hung kit where at least 3 weeks lead time is available. Standard jambs can be either primed MDF (18mm thick) or finger jointed pine (19mm thick) for 2040 or 2340 door heights & single or double door configurations in the following sizes:

Loose rectangular door stops are included with frame kits. Pre hung kits are hung on 2 hinges and the handing of the door is determined from the visible hinge knuckles as seen on right. Pre hung units can be ordered as double hinged only or with a 25 or 54mm lock hole and optional latch fitted, lift off hinges or with the option of 3 hinges.

DO YOU SELL CAVITY SLIDING UNITS?

Most commonly available cavity sliding units only permit 35mm thick doors but are available for 2340 as well as 2040 door heights. This is a significant constraint with many timber joinery doors being 40mm thick which requires a cavity unit ideally made for 100mm studwork. You can squeeze a 40mm door into a 90mm stud cavity unit but any warps or bow will cause problems. Standard lightweight domestic cavity units carry loads up to 65kg and are available to suit stud thicknesses of 70, 75, 90 and 100mm and come with the cavity pocket, head track assembly, removable pelmet, glide guide kit and trolley kit. They are made as either reversible single units or double units in the following sizes.

It is never a good idea to use cavity sliding units on external walls as they become a haven for vermin, insects and sometimes even snakes or possums.

WHAT ABOUT WARDROBE DOORS?

Almost any door can be used in a wardrobe application although hinged or sliding options are most popular. Proprietory Sliding units from Corinthian are limited to 35mm thick doors and come made for 2, 3 or 4 door applications for standard height 2040 doors (requiring a stud opening of 2100mm) or 2340 doors (needing a stud opening height of 2400mm). The track is either satin silver or white in colour and the doors have a choice of either factory fitted timber handgrips or site installed flush pulls. The standard sizes for each application are as follows

WHAT ABOUT INTERNAL BIFOLDING APPLICATIONS?

Just about any internal space can be divided by overhead tracked folding doors, provided sufficient structural support is available to carry the weight. The systems available are as follows

Lightweight Bifolds
Typically these are two hollow core doors hung on an overhead track and can utilize individual doors up to 920mm wide but more commonly use half doors to achieve standard openings 2040 x 820/770/720 & 620. Off the shelf bifolds use doors 2015mm high rather than 2040mm high so that they align with any adjacent hinged doors. They typically require a stud opening 2080 high (minimum).

Heights are calculated as follows using an 820 door as the example
Height of leaf	= 2015mm
Allowance for track and fittings	= 23mm
Clearance at bottom for pivot	= 20mm
(add any extra clearance for floor coverings)
19mm jamb thickness	= 19mm
Standard opening height	2077mm
Widths calculated as follows
Leaf width x number of leaves (405 x 2)	= 810mm
Add 6mm either side for pivot + clearance	= 12mm
Add 1.5mm per centre hinge knuckle	= 1.5mm
Add jamb thickness 19mm x 2	= 38mm
Fitting clearance to studs 4mm x 2	= 8mm
	869.5mm

Because lightweight doors permit very limited trimming the sizes of these units need to be standard. Standard hardware is limited to bright chrome or gold finish.

Lightweight Multifolds
Typically these are two hollow core doors hung on an overhead track and can utilize individual doors up to 920mm wide but more commonly use half doors to achieve standard openings 2040 x 820/770/720 & 620. Off the shelf bifolds use doors 2015mm high rather than 2040mm high so that they align with any adjacent hinged doors. They typically require a stud opening 2080 high (minimum).

Large opening multifolds
For larger openings the cost of so many door leaves starts to become prohibitive and it is more economic to move to heavier duty tracks and larger doors provided sufficient stow space is available.