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CONNECTING DORMERS TOGETHER
NEW AND OLD FOR PARTY WALL MATTERS
Navigating Dormer Design Challenges in Loft Conversions
When planning your dream loft conversion, adding that extra bedroom can be an exciting venture. However, if your neighbor has already constructed their dormer, you may encounter a few challenges. While your dormer design might aim to maximize the width within permitted development (PD) rules, the actual construction could face limitations. Builders often find it difficult to extend the dormer fully to the boundary due to access issues for tiling and installing lead flashings.
Typically, builders require a minimum gap of 400 mm to install side dormer tiles, fix lead flashings, and ensure proper construction. If your neighbor’s dormer was built first, this could result in your loft extension being narrower than theirs.
At Discount Plans Architectural Design Studio, we recommend appointing a **Party Wall Surveyor** to resolve these issues. By collaborating with your neighbors and obtaining a party wall agreement, you can potentially join the two dormers together. This will allow both properties to achieve a balanced design, ensuring equal widths for both loft conversions.
What are all the BENEFITS of MERGING your new dormer to your neighbour's existing dormer?
Connecting a new dormer to an existing dormer involves carefully integrating the structure, flashing, and roofing materials to ensure weatherproofing and a seamless appearance. Below is a step-by-step explanation of how to connect a new dormer to an existing dormer, with specific details about sealing with lead flashing and interlocking tiles on the rear face wall:
1. Assessment and Planning
Structural Assessment: Before beginning, assess the existing dormer structure to ensure it can support the additional load of the new dormer. Check for any structural issues, such as rot or damage, that need repair.
- Design and Measurements: Plan the size, shape, and position of the new dormer in relation to the existing dormer. Ensure that the design complies with local building codes and regulations.
2. Framework Construction
- Cut Roof and Install Dormer Frame: Carefully cut the existing roof where the new dormer will be attached. Construct the framework for the new dormer using timber, ensuring the new frame aligns with the existing dormer's structure.
- Join Dormer Structures:** Securely join the new dormer's framework to the existing dormer using appropriate fasteners, brackets, and joists. Ensure that the connection is strong and capable of withstanding environmental stress.
3. Roofing and Wall Integration
- Roofing Alignment: Align the new dormer's roof with the existing dormer roof. The roof pitch should be the same to allow for smooth water runoff and aesthetic consistency. The connection point should be sealed with proper underlayment to prevent leaks.
- Interlocking Tiles on Rear Face Wall: Where the new dormer connects with the rear face wall of the existing dormer, remove some of the existing tiles. Install new tiles that interlock with both the existing and new tiles. The tiles should overlap appropriately to ensure that water runs off correctly and does not penetrate the joint.
4. Lead Flashing Installation
- Prepare Lead Flashing: Use code-compliant lead flashing, typically with a thickness of 1.8mm to 2.0mm, which is durable and flexible enough to shape around dormer structures.
- Install Lead Flashing Around the Joint:
- Chase out mortar joints on the existing dormer wall where the new dormer will join. This creates a slot to insert the lead flashing.
- Insert the lead flashing into the chase, ensuring it covers the joint between the new and existing dormers. The flashing should extend a minimum of 150mm up the new dormer walls and cover the roof's edge. The flashing is then dressed down over the roof tiles or slates to direct water away from the joint.
- Secure the lead flashing with lead wedges and seal the chase with lead-compatible mortar to ensure a tight fit.
- Overlap Flashing: Ensure that each section of lead flashing overlaps the one below by at least 100mm. This prevents water from seeping in through the joints. Use a suitable sealant where the flashing overlaps to provide additional waterproofing.
5. Waterproofing and Final Inspection
- Check Seal Integrity: After the lead flashing and tiles are installed, inspect the joint to ensure no gaps or loose areas could allow water infiltration.
- Conduct a Water Test: Spray water over the joint area to check for leaks. Address any leaks immediately by adjusting or adding additional flashing or sealant.
- Final Inspection: Check the overall dormer connection for structural integrity, flashing coverage, and tile alignment. Ensure everything is securely fastened and weatherproof.
6. Finishing
- Internal Finishing: Once the exterior is weatherproofed, proceed with internal insulation, drywall, and other finishing touches inside the new dormer.
- Exterior Cladding and Trim: Apply cladding or trim to the new dormer to match the existing dormer, ensuring a seamless appearance.
By following these steps, the new dormer can be effectively connected to the existing dormer with proper waterproofing, using lead flashing and interlocking tiles, ensuring both structural integrity and aesthetic continuity.
PARTY WALL LONDON LIMITED
based in North London, specializes in resolving dormer-related matters between neighboring properties. Their expert team ensures a fair and balanced approach, helping you and your neighbours seamlessly merge dormers for optimal design and equal benefit to both properties.
EACH PROJECT WE TAKE ON IS STARTED FROM SCRATCH SO EVERY NEW JOB IS DESIGNED WITH CARE AND EXPERTISE TO GET 100% SATISFACTION
Contact our team today for a free qoutation
Remember that if you are choosing more than one design you will be offered a further discount on any other second design.
We will not be beaten on price and if we are we will offer you a price match service in design* subject to agreement.
I hope you found this article useful for your proposed loft conversion proposal, join1000s of other satisfied customers whom we have helped design to their tailored layout.
Regards John.