Technical note: Securing windows and doors

Introduction

A listed building owner’s statutory obligations remain exactly as they were when the building was in full use, even when a property is empty and nobody lives or works there. While there is no specific duty on owners to keep their historic buildings in a good state of repair it will normally be in their interests to do so. The Department has no powers to intervene where a building’s condition is considered to affect the amenity of an area but it does have statutory powers to take action where an historic building has deteriorated to the extent that its preservation may be at risk (Articles 80 and 109 of the Planning Order (NI) 1991). 

It is also sensible that owners continue to bear in mind health and safety and duty of care to the public. That duty can pose problems, particularly in the area of insurance. When a building is unoccupied, the risks of malicious arson, criminal damage, squatting and other criminal activities are dramatically increased, and insurers may exclude cover during periods when buildings are vacant. Obtaining new insurance for a building that has become vacant can be very difficult unless you have taken reasonable steps to protect it and reduce risks.

Risk control measures 

1. Inform your insurers that the building is empty Insurers may expect you to take reasonable steps to protect your empty property. 
2. Provide details of Key-holders to the local Police. 
3. Consider engaging a specialist firm to look after security. 
4. Turn off water and electricity at the mains. All water tanks and water filled plumbing should be completely drained - unless heating is maintained via suitable thermostatic controls to ensure that pipes do not freeze. 
5. Regular inspection. Ensure that the premises are visited and inspected, externally and internally, on a regular (weekly) basis. Pay particular attention to gutters and valleys on the roof. These are where water ingress begins first. 
6. As a last resort consider removal of valuable or vulnerable items in agreement with NIEA:HBU. This could include fireplaces fixed artwork or delicate/ ornamental joinery. Any removed items should be recorded and placed in a secure store. They remain part of the protected fabric and ownership transfers with the building. Listed building consent will be required.
7. The exterior of the premises should be cleared of rubbish and any flammable materials such as scrap wood builder’s materials etc. Drain fuel tanks if they are accessible to trespassers. 
8. Secure the site perimeter. Security fencing should be erected, where appropriate, to provide total protection to the site. Gates should be of equal integrity to the fencing and fitted with good quality locking devices.
9. If an intruder alarm installed it should be retained and regular maintenance be continued. Consider installing an intruder alarm system with a “dial up” warning. 

Windows and doors 

For an unoccupied building the highest risk of unauthorized access is through windows and doors. Windows and doors form an important part of the historic fabric of listed buildings and are considered to be important elements of an historic buildings architectural and historic character. Forced entry can mean damage or destruction of these elements in addition to any subsequent internal vandalism. However securing the windows and doors properly can prove a cost effective and efficient deterrent to break ins.

As is set out in other technical guides windows and doors in historic buildings form an important element in their internal ventilation. These elements are normally considerably more pervious to air movement than their modern equivalents. The high level of ventilation plays an important part in controlling the level of moisture present in the historic fabric.

Unsuitable blocking or covering of windows can lead to a severe reduction of ventilation to an historic building. As a result internal humidity rises to a level which permits the rapid development of dry and wet rot. An enormous amount of damage can occur in a very short space of time. 

It must also be borne in mind that the historic fabric of the windows doors and their surrounds should be preserved. Screens which are mechanically fixed to the wooden frames or to the stone and brick surrounds of openings can risk irreversible damage to important decorative fine details. It should be possible to remove any security shutters and leave no detectable evidence of their presence on historic stone brick wood and glass.

Unsuitable methods 

Solid steel sheet 

Solid steel sheets fixed to windows and doors are not recommended by NIEA:HBU as a suitable security measure. 

The sheet steel screens shown right allow no air movement through the openings and lead to a very high risk of dry rot. The heavy fixings may damage wooden window frames particularly the fine joinery associated with sliding sash windows. It can prove impossible to locate heavy screw bolts without breaking historic glass. If brackets are used instead then the damage is transferred to the window reveals. In listed buildings these are frequently carved stone or fine brick difficult or impossible to repair. 

If the fixings are left with functioning screw heads they can be easily removed by intruders, if the heads are stripped then eventual removal for renovation is a problem. Each screen must be made to fit the exact dimensions of the structural window opening. In a listed building with non modular or standardised openings this leads to a need for time consuming and expensive alterations of sheets.

Bricked up openings 

Infilling openings with masonry is not recommended by NIEA: HBU as a suitable security measure. There is a high risk of damage to the historic joinery and historic glass. Damage can occur during construction of the infill and even more so during attempts to remove it. There is also a risk of damage to the reveals of the windows in attempts to key the new masonry to the old. The same issues of ventilation apply as for any imperforate material. It can be difficult to fix screened openings into a sheet of blockwork.

Low-medium security 

On some buildings the risk of unauthorized entry is low. This may be where there are no high value salvage items such as fireplaces and doors, or If the building is in a quiet residential area and overlooked. It may be remote from a population centre and away from view of the general public but visited regularly by the owner. Alternatively the building may be on a busy thoroughfare and benefit from being under the public gaze.

Plywood/timber particle board 

Where the risk of forced entry is low then plywood sheets have proved effective. The plywood should be 9mm minimum thick and WBP grade or the equivalent in an OS or particle board. The shutter should be cut to the profile of the window to cover glass and frame. Fixings should be non ferrous and care must be taken with positioning to avoid damage to the frames or glass. An open panel of approximately 250x400 with a fine metal anti vermin mesh should be located to allow ventilation through the (open) window or door behind the shutter.

High security applications 

Peforated steel shutter systems 

The preferred option is to use pre fabricated standard steel shutters. The external component of the shutters comprises a rigid box frame with a sheet steel shell. The sheet steel has perforated sections to allow ventilation and light penetration. 

There are manufacturers who will hire or sell screens similar to those illustrated. All screens shown below are the property of the NIHE. 

Wires are drawn from the back of the screen and brought into the building through the opened windows. Inside the building a ratchet draws the wire tight against adjustable struts which span the opening.

Low risk applications 

There are several UK and European based firms who run guardian schemes, looking after empty houses and commercial premises. The firms recruit individuals to act in a janitorial capacity in exchange for paying a modest rent. The firms recruit individuals who want a flexible lifestyle and are comfortable with an alternative to conventional home ownership or renting.

Do’s and don’t 

Do: 

• contact NIEA:HBU for advice. 
• maintain regular inspections to identify leaks or decay 

Don’t: 

• seal the building making it airtight 
• damage the windows or doors fitting the screens • Allow leaks from gutters or roof to develop undetected

Useful contacts / further reading 

• British Standards: 
  BS 7913:1998 Guide to the principles of the conservation of historic buildings. 
• Some helpful publications: 
  Period Houses, A Conservation Guidance Manual. 
  Dublin Civic Trust 2001. 
  Chapter 8 Roofs and Roof Coverings.
  Traditional Buildings in Ireland Home Owners Handbook 
• Advisory Organisations: 
  The Ulster Architectural Heritage Society (UAHS) has a Directory of Traditional Building Skills 
  The National Inventory of Architectural Heritage (NIAH) www.buildingsofireland.ie