THE TRJ JOURNAL · SIP construction

SIP Panels vs Timber Frame

By Constantin Tiseanu · · 2 min read

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SIP Panels vs Timber Frame

Building with SIP Panels Versus Timber Frames

SIP panel walls for garden room

     When it comes to constructing a building, there are various materials and techniques to choose from. In this guide, we will explain the advantages of building with SIP panels instead of timber frames.

Energy Efficiency

Thermal performance depends on the complete wall, roof and floor build-up, insulation core, joints, glazing and workmanship. Compare specified systems and calculated U-values rather than assuming every SIP system outperforms every timber frame.

Strength and Durability

SIP Panels

SIP strength and permissible spans depend on the panel system, loading, connections and manufacturer’s design information. Both SIP and timber-frame buildings require appropriate structural engineering.

Timber Frames

Timber-frame performance also depends on engineering, moisture protection and installation. Material choice alone does not establish support capacity or durability.

Faster Construction Time

Pre-cut Panels

  SIP panels are prefabricated according to your specifications in a controlled factory environment. This means they can be delivered to the site and quickly assembled, reducing the need for on-site cutting and assembly.

Quick Assembly

Factory-prepared panels can reduce time spent assembling the structural envelope on site. The overall programme still includes foundations, services, finishes and any approvals.

Cost Factor

                                                                                SIP Panels                                               Timber Frames                                 

Material Cost                                               Higher upfront cost                                    Lower upfront cost                           

Installation Cost                                         Lower installation cost                               Higher installation cost

Long-Term Maintenance              Lower long-term maintenance cost            Higher long-term maintenance cost

    Overall, the cost-effectiveness of SIP panels depends on the project's scope and intended use. While SIP panels tend to be more expensive upfront, they can help save money in the long run through lower energy costs and maintenance.

Environmental comparison should use product declarations, transport, installation and whole-life assumptions for the actual designs. A lower carbon footprint cannot be assumed from the construction label alone.

      While both SIP panels and timber frames have unique advantages and disadvantages, when it comes to energy efficiency, strength and durability, construction time, cost-effectiveness, environmental impact, design flexibility, and maintenance requirements, SIP panels emerge as the better option. SIP panels provide homeowners with a more energy-efficient, cost-effective, and visually stunning building that is highly durable and requires little maintenance over time.

Sources and project-specific guidance

Check the current guidance and the actual project specification. Performance, cost and approval depend on the complete design and site.

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PLAN YOUR BUILD WITH TRJ

What should you know before choosing a garden room or annexe?

Meet our founder: , founder and director of TRJ Construction Ltd. Updated .

TRJ Construction Ltd designs and builds SIP garden rooms, granny annexes and house extensions. We work across Hertfordshire, North London, Essex, Buckinghamshire and surrounding areas. The right specification starts with how you will use the building, the site conditions and the services it needs. A home office, a gym and an annexe for independent living have different requirements.

Which type of building suits your project?

Choose the building around its intended use. A garden room can provide a separate place to work, exercise or relax. An annexe needs a layout and facilities suitable for its proposed residential use. A house extension changes the existing home and needs its structure and services considered together.

Compare the main TRJ building options
BuildingTypical useKey decisions
Garden roomOffice, gym, studio or family spaceFloor loading, glazing, heating and any bathroom facilities
Granny annexeIndependent living spaceKitchen, bathroom, accessibility, services and planning status
House extensionAdditional space connected to the homeExisting structure, openings, roof design and building control

What SIP specification does TRJ use?

Our published specification includes 125 mm structural insulated wall panels and 150 mm SIP panels for roofs and bases. The final design must account for the particular building, structural loads, moisture control, ventilation and finishes. Panel thickness alone does not establish the performance of the completed building.

  • 125 mm: the wall-panel specification described in our company information.
  • 150 mm: the roof and base panel specification described there.
  • Since 2012: TRJ Construction Ltd has been led by Costi Tiseanu, whose construction experience spans more than 25 years.

Read Costi’s experience and TRJ’s specification, or see how our buildings are constructed. These are details about our work, rather than industry-wide performance claims.

How do you start a garden-building project?

  1. Describe the use. Tell us whether the building is for work, exercise, hobbies or living accommodation.
  2. Share the site information. Send photographs, approximate dimensions, access details and any existing drawings.
  3. Review the requirements. Discuss planning, building control, foundations, drainage and electrical connections.
  4. Agree the specification. Confirm the layout, materials, fit-out and the items included in the quotation before work begins.

Our completed projects show real examples. Where a project was built by TRJ for Garden Spaces, the case study identifies that relationship.

What questions do clients ask?

Can a garden room be used all year round?

Yes, a garden room can be designed for year-round use. The specification needs suitable insulation, heating, ventilation and moisture control. We discuss the intended use and site conditions before agreeing the build.

Can TRJ include a bathroom or kitchenette?

Yes. TRJ builds garden rooms and annexes with bathrooms and kitchen facilities. The layout, drainage route, water supply, electrical requirements and applicable approvals need to be assessed for the site.

Does every garden room need planning permission?

No single answer applies to every site. Some outbuildings may qualify as permitted development, subject to limits and conditions. Location, dimensions, previous permissions and intended use matter. Living accommodation needs particular care. Check the proposal with the local planning authority before building.

How much will my building cost?

The price depends on floor area, access, foundations, glazing, services and interior finishes. Use our annexe cost guide as a starting point, then request a quotation for your site and agreed specification.

Explore annexe costs · View rooms with bathrooms · Discuss your project