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Loft Conversion Guide

Loft Conversions are an excellent way of adding all important space to your property. Depending on the size and footprint of your home, they can easily allow for an additional bedroom and in larger properties can even accommodate an ensuite or an office study.

Alongside planning requirements and building regulations, the Party Wall etc Act 1996 will also need to be considered and adhered to. As with any construction work, loft conversions carry a risk, part of mitigating that risk is going through the necessary Party Wall Surveying procedures.

We thought we would take a look at Loft Conversions through a Party Wall Surveying perspective in the hope of helping you understand the type of considerations that Party Wall Surveyors will look if they act for you or for your neighbour.

Structural Calculations

Structural Calculations will be prepared by the building owner’s (the neighbour undertaking the works) Structural Engineer and will ensure that the added load of the loft extension can be adequately supported by the existing structure and Party Wall.

Loft Conversions will likely see the addition of 1 to 4 beams inserted into the Party Wall. Commonly a ridge beam will support the pitch of the new loft roof and 3 to 4 beams will support the new loft room floor. These structural additions increase the weight and load to the Party Wall therefore it is vital that the current structure is properly considered.

While your Party Wall Surveyor is unlikely to review or check the calculations, they are likely to make enquires into the Engineer who has prepared them to ensure that they are suitably qualified.

The Party Wall etc Act 1996 does allow a Party Wall Surveyor to call upon the services of their own engineer to advise them. However, this request tends to be reserved for highly complex structural design and works such as basement extensions or underpinning.

Ensuring Half the thickness of the Party Wall is Used

The majority or semi-detached or terraced properties are separated by a solid construction wall with a thickness of 225mm (9 inches) or the length of a brick.

Under the Party Wall etc Act 1996, the building owner has the legal right to use the full thickness of the Party Wall to accommodate their loft conversion, however if they were to do this it would prejudice the adjoining owner’s (the neighbouring owner) future development plans.

Through the agreement of a Party Wall Award, the Party Wall Surveyor will ensure that the plans and proposals only allow the building owner to use half of the thickness of the Party Wall or up to 112mm (4.5 inches) for insertion of the proposed beams.

This will ensure that the adjoining owner is able to undertake a similar loft conversion in the future without having to design around the building owner’s extension.

Ensuring Open Chimney Breasts or Vents are Covered  

The insertion of steel beams into a Party Wall facilitating the loft conversion will mean that pockets or openings are cut into the Party Wall to allow the beams to rest on the Party Wall. The pockets are usually 300mm by 300mm (12 inches by 12 inches) in size.

The percussive nature of cutting these pockets into the Party Wall will cause vibrations to the wall and likely dislodge any friable brickwork, or soot if the neighbouring property has chimney breasts.

If the neighbouring property has open chimney breasts or vents on the Party Wall, this brickwork and soot will inevitably find its way into the adjoining owner’s property and as a result will cause dust and dirt damage to the property, walls, floors and carpets.

Through the agreement of a Party Wall Award, the Party Wall Surveyor will ensure that the adjoining owner’s property is well considered pre works and temporary protections, in the form of heavy duty polythene sheeting is lightly taped over these openings.

Another option is to install a chimney balloon that is just as effective. This is a simple step to take and easy install solution, however it has great benefits against preventing damage.

Temporary Party Wall Weathering

During the process of undertaking the loft extension, the building owner will be exposing the Party Wall by removing their existing roof covering and the roof structure beneath it.

Through the agreement of a Party Wall Award, the Party Wall Surveyor will ensure that once the Party Wall is exposed, it is adequately weathered to ensure that rain and moisture doesn’t transfer through the exposed wall into the adjoining owner’s property and cause penetrating damp.

Generally speaking, there are two different ways to weather proof an exposed wall: Weatherproofed Scaffolding, which will be in the form of metal sheeting at roof level, with the scaffolding then being encapsulated in sheeting. The other is directly weatherproofing to the exposed wall in the form of roofing felt or plastic sheeting fixed directly to the exposed Party Wall, with the sheeting then held in place with timber battens.

Damage caused by damp and moisture can be a costly repair, this temporary precaution is a must for any loft conversion.

Contractor Hand Tool Use

In order for the contractor to insert the steel beams into the Party Wall, they will need to cut pockets into the wall facilitating the beams. As confirmed above, these works will cause vibrations to the Party Wall which can not only lead to lose brickwork and soot, but can also lead to cracking and damage.

A contractor’s natural tool of choice for cutting into a Party Wall for the creation of the pockets will be a pneumatic hammer or kango as it is quick and efficient. However, it is also incredibly percussive and almost always leads to damage to the adjoining owner’s property.

Through the agreement of a Party Wall Award, the Party Wall Surveyor will ensure that the contractors can only use hand tools for any works directly to the Party Wall. This greatly reduces the vibrations associated with the works and ensures the chances of damage are kept to a minimum.

Installation of Scaffolding Alarms

During the process of undertaking the loft conversion there will be scaffolding erected to the front and rear of the building owner’s property (the neighbour undertaking the works).

If the adjoining owner (the neighbour adjoining the works) has a rear extension with a flat roof, or the property is constructed in such a way where there could be easy access from the scaffolding. Through the agreement of a Party Wall Award, the Party Wall Surveyor will ensure that scaffolding alarms need to be installed with clear signage to all facades of the building owner’s scaffolding.

As with any alarm, the scaffolding alarm will ensure that any unauthorised access sets off the alarm which will ensure an appropriate company and person is made aware and takes the necessary action to investigate the trigger.

Scaffolding alarms aren’t required on all loft conversions and it will be very much specific on the lay of the land and surrounding properties.

Cantilevered Scaffolding Access

If the building owner’s proposed loft dormer is built close to the party wall, or includes raising the party parapet wall. In order to construct the flank wall or face of the dormer, the contractor will require access onto the adjoining owner’s roof.

A contractor’s method of choice for access onto an adjoining owner’s roof will be via a roof/hook ladder or by simply standing on the tiled surface. Both of these options add pressure to the roof covering and also don’t include any protection or barrier from the building site.

Cantilevered Scaffolding ensures that contractors aren’t treading, walking or working from an adjoining owner’s roof and therefore ensures that broken roof tiles, slipped roof tiles or damaged flat or glazed roofs are one less concern during the course of the work.

There is also a clear screen and separation from the building works and the adjoining owner’s property, ensuring that cement splash, dust, tools, material and workmen all stay off an adjoining owner’s property.

Through the agreement of a Party Wall Award, the Party Wall Surveyor will ensure that if necessary scaffolding such as this is installed, preventing issue and damage.

Party Wall Award Timing

In our experience agreeing a Party Wall Award for a proposed Loft Conversion is a relatively straightforward process, however there can be delays around the Party Wall Notice response stage and also around the timings of arranging a pre works Schedule of Condition Report of the adjoining owner’s property.

We would suggest budgeting in the region of 1 to 2 months from the point at which Party Wall Notices are served.

We recommend taking this into account when planning a start date, the last thing you will want is the contractor raring to go, with Party Wall Awards still some way off being agreed.

This timescale would also assume that all of the necessary information is in place such as the structural calculations and drawings.

Loft Conversion Costs

Loft Conversions are by no means a low cost form of construction. Depending on the type of property, the location and the proposed size of the conversion, the costs are likely to be upwards of £80,000.

That being said with London Property Prices going up, the investment into the added space of a Loft Conversion could be well worth it.

We think Loft Conversions are a fantastic way to get the most out of your home and ensure that you are making the most of its potential.

What to know more or speak to one of our Surveyors?

We undertake hundreds of Loft Conversion Party Wall Surveying jobs each year throughout England and Wales.

Over the years we have dealt with pretty much every type of issue imaginable on Loft Conversions and would be happy to discuss your proposed work.

Give our team of experienced Surveyors a call now.

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