Before installing the FG110F double inward-opening thermal break window, why is it necessary to first confirm the opening dimensions and wall conditions?
The FG110F double inward-opening thermal break window adopts a double inward-opening structure, with the sashes opening toward the interior. This means that the connection method between the window frame and the opening, the load-bearing path, and the sealing strategy are all directly determined by the opening dimensions and wall conditions. If these two factors are not clearly confirmed before installation, subsequent problems such as water seepage, sash sagging, and difficulty in opening and closing are often difficult to remedy by adjusting hardware or applying sealant.
Opening Dimension Verification: Reserved Clearance and Tolerance Range
The reference configuration for the FG110F double inward-opening thermal break window is 1000×1000mm, but in actual projects, the opening dimensions are almost never exactly the same as the window frame dimensions. Before installation, three data points need to be verified: the opening width, height, and diagonal length.
- Reserved Clearance: The opening dimensions should be larger than the outer dimensions of the window frame, with a conventional reserved clearance of 15-25mm.This gap is used to adjust the levelness and verticality of the window frame, while also leaving space for foam filling.If the gap is too small, the window frame cannot be leveled;if the gap is too large, the filling layer will be too thick, and after long-term shrinkage, micro-cracks are likely to form between the window frame and the wall.
- Tolerance range: The deviation of the opening width and height is recommended to be controlled within ±5mm, and the diagonal deviation should not exceed 3mm.If the actual size of the opening exceeds this range, the opening needs to be trimmed or leveled first, rather than forcibly inserting the window frame.Forced installation will cause deformation of the window frame, directly affecting the sealing tightness of the double inward-opening sashes.
Special attention should be paid to the fact that when the sashes of a double inward-opening window are fully opened, they will occupy indoor space. If the opening is located near a corner, curtain box, or furniture placement area, it is also necessary to confirm that there are no obstacles within the opening radius of the sashes. Although this item is not part of dimensional verification, it is recommended to record it during measurement.
Influence of wall type and load-bearing conditions on installation methods
The FG110F double inward-opening thermal break window has a profile thickness of 2.0mm, and the sash is relatively heavy. When opened, all weight is transferred through the hinges to the frame, and then to the wall. Therefore, the wall must have sufficient load-bearing capacity and anchoring conditions.
- Concrete wall: The anchoring points have sufficient load-bearing capacity, and standard expansion bolts or special anchor bolts can be used.During installation, pay attention to avoiding rebar when drilling holes, and it is recommended to control the anchor bolt spacing at 300-500mm.
- Brick wall (solid brick or perforated brick): The load-bearing capacity is acceptable, but drilling may easily encounter brick joints or hollow areas.Depending on the site conditions, it is necessary to choose extended expansion bolts or chemical anchor bolts, and the anchoring points should be placed as much as possible on the solid parts of the brick body, avoiding all being on the mortar joints.
- Lightweight walls (aerated blocks, hollow bricks, light steel keel walls): Such walls have limited load-bearing capacity themselves, and directly anchoring the window frame poses a risk of loosening.For double inward-opening windows like the FG110F, if the wall is a lightweight structure, it is necessary to first confirm whether the wall has been reinforced (such as pouring structural columns or adding steel sub-frames). Otherwise, after long-term opening and closing of the sash, the anchoring points on the hinge side may gradually loosen, causing the sash to sag.
Recommendation for judgment: If the project wall is concrete or solid brick, and the opening dimensions are within the tolerance range, the FG110F double inward-opening thermal break window can be installed directly according to the standard procedure. If the wall is lightweight or the opening deviation exceeds ±5mm, it is necessary to first provide the wall structure and actual opening measurements to the Haipaisi Chuang team to confirm whether steel sub-frames need to be added or the anchoring plan adjusted, before proceeding with installation.
FG110F Double inward-opening thermal break window frame fixing and leveling: Why is it said that 'a minor error at the start leads to a major mistake at the end'?
The FG110F double inward-opening thermal break window uses 6063-T5 aluminum alloy profiles with a wall thickness of 2.0mm. The frame stiffness is sufficient, but sufficient stiffness does not mean that installation can be careless. The double inward-opening structure means that the entire weight of the sash is transmitted to the frame through the hinges. Once the frame is tilted, the compression of the sealing strips when the sash closes will be uneven—one side is compressed tightly, while the other side leaks air. Over time, this can also cause the hinges to bear load on one side, leading to sagging or even detachment. This is the practical consequence of 'a minor error at the start leads to a major mistake at the end'.
Core steps for frame fixing: temporary fixing, leveling, and final fixing
Step 1: Temporary fixing. After placing the frame into the opening, first use wooden wedges or special pads to support the four corners and the mullion positions, then use expansion bolts or fixing plates for temporary fixing. The purpose of temporary fixing is to prevent the frame from moving, but do not tighten it all at once; leave room for adjustment.
Step 2: Alignment. This is the step that determines success or failure. Use a spirit level and a laser plumb line to check the levelness of the top frame of the window frame, the verticality of both side frames, and the difference in diagonal lengths of the frame.
The recommended alignment sequence is: first adjust the level, then the vertical, and finally recheck the diagonals. The FG110F double inward-opening window frame profile is relatively deep. During alignment, pay attention to frame torsion—checking the verticality of one side alone is not enough; also verify that the side of the frame is parallel to the wall.
Step 3: Final fixing. After alignment passes inspection, tighten all fixing points in order. Tighten the fixing points sequentially from both ends toward the middle to avoid locking one side first, which could cause the frame to twist.
After final fixing is completed, the levelness and verticality should be re-measured to confirm that no displacement has occurred due to tightening.
Leveling standard: allowable deviation for levelness and verticality
Referring to the general acceptance requirements for aluminum alloy door and window projects, after the window frame is installed:
- Levelness deviation: no more than 2mm per meter of length, and the total deviation of the entire frame should not exceed 3mm;
- Verticality deviation: no more than 2mm per meter of height, and the total deviation of the entire frame should not exceed 3mm;
- Diagonal length difference: The diagonal difference of the frame shall not exceed 3mm.
The above values are the industry-standard acceptance criteria. For the specific allowable tolerance range of the FG110F double inward-opening window, it is recommended to confirm the factory installation guidelines with the Haipaisichuang team when placing an order, and those guidelines shall prevail.
What is the appropriate spacing for fixing points?
The spacing of fixing points is not better when denser, nor is it more convenient when sparser. The conventional practice is:
- The fixing points shall be no more than 150-200mm from the corners of the window frame;
- The spacing between intermediate fixing points shall not exceed 500-600mm;
- For double inward-opening windows, the fixing points on the hinge side and the locking side should be densified, with the recommended spacing controlled within 400mm, as these positions bear the greatest dynamic loads.
If your project has a large opening size (over 1500mm wide), or if the area has high wind pressure, the spacing between fixing points should be tightened accordingly. The specific spacing depends on the opening size, wall material, and wind load level. You need to provide the opening size and project location to the Hipex Creative team, and confirm the matching solution before construction.
Common mistakes to avoid: Do not use foam sealant to bear structural loads instead of fasteners. Foam sealant is only for filling and insulation, not for structural fixing. The FG110F double inward-opening window frame is heavy and must be securely connected to the wall using expansion bolts or fixing plates.
Additionally, fixing plates must not be attached to mortar joints; they should be anchored into concrete or solid masonry blocks.
Waterproof sealing treatment: Why is 'caulking' the most problematic step in inward-opening window installation?
For inward-opening windows, waterproof sealing problems often arise in the 'caulking' step. Caulking is the last visible remedial step—any previous step that wasn't done well will be exposed during caulking, and caulking itself is easily regarded as a 'universal remedy'.
Three levels of waterproof sealing: exterior wall waterproofing, filling the gap between the window frame and the wall, and interior sealing
The waterproof sealing of the FG110F double inward-opening thermal break window is not just 'applying a bead of sealant'—it involves three levels, each with its own role:
First level: exterior wall waterproofing. This is the first barrier preventing rainwater from entering the gap between the window frame and the wall, relying on waterproof mortar or a dedicated waterproof membrane on the outside of the frame, as well as the drainage slope of the window sill. If this level is not done well, rainwater will directly seep into the gap, and no amount of interior caulking can stop it.
Second level: filling the gap between the window frame and the wall. The correct approach is to fill the gap between the window frame and the wall with polyurethane foam, and after it cures, trim it flush. The foam's role is to fill, insulate, and provide auxiliary fixation; it is not a waterproof layer.
The actual waterproofing is handled by the waterproof layer on the outside of the gap and the sealant on the inside.
Third layer: interior sealing. On the interior side, apply a continuous, uniform bead of sealant at the junction between the window frame and the wall to prevent moisture infiltration and air leakage.
For double inward-opening thermal break windows like the FG110F, all three layers are indispensable. The thermal break aluminum profile solves the heat and cold conduction issue within the frame itself, but if the gap between the frame and the wall is not treated with the three-layer method, the performance advantages of the profile will be negated by installation defects.
Common sealing mistakes: applying sealant too thickly, discontinuous sealant beads, and using low-quality sealant.
Three errors occur most frequently, and all directly affect the long-term sealing performance of the FG110F double inward-opening broken-bridge window:
1. Applying sealant too thickly. When the sealant thickness exceeds its allowable range, the interior cannot fully cure, making it prone to cracking. The correct approach is to control the ratio of sealant joint width to depth at approximately 2:1, with the sealant layer thickness generally not exceeding 6mm.
When the gap is too wide, it should first be filled with foam filler rather than being packed with sealant.
2. Discontinuous sealant joints. Pausing mid-application, overlapping or breaking at joints during sealant application can create water infiltration paths. The four corners of an inward-opening window are the most prone to missed or thinly applied sealant.
The correct approach is to apply the entire bead of sealant in one continuous pass, without breaking the bead at corners.
3. Using low-quality sealant. Low-quality sealant does not meet the required weather resistance and bond strength. After intense summer sun or low winter temperatures, it is prone to cracking, chalking, or debonding from the profiles. For sealant used at the junction between the window frame and the wall, choose a neutral silicone sealant and confirm that its stated movement capability and weather resistance rating are suitable for exterior window applications.
It is important to note:Expanding foam is not sealant, and sealant is not a filler material. The two have different functions and cannot be used interchangeably. Expanding foam is responsible for filling the space, while sealant is responsible for surface sealing.
Hardware adjustment and glass installation: Why does the 'final step' of inward-opening windows determine long-term user experience?
Sash sagging, poor locking, and air leakage from weatherstripping—these issues rarely stem from the profile itself, but rather from inadequate hardware adjustment and glass installation during the final installation phase. For large-sash inward-opening windows like the FG110F double inward-opening thermal break window, this step directly determines the feel of use three to five years down the line.
Hardware adjustment: Coordination of locking points, hinges, and transmission mechanisms
The core of adjusting the FG110F double inward-opening window is to ensure that the locking points, transmission mechanisms, and hinges form a smooth linkage line. During installation, follow this sequence:
- Adjust the hinges first, then the locking points. The hinges serve as the positioning reference for the sash.Use a hex wrench to adjust the eccentric screws on the hinges so that the gap between the sash and the frame is even on all sides—typically controlled at 3-5mm, with a deviation of no more than 1mm in any direction.If the hinges are not leveled, no amount of adjusting the locking points will help.
- Center the transmission gear. When installing the transmission gear, ensure that when the handle is in the closed position, the locking points on the transmission rod align exactly with the locking blocks on the frame.If the deviation exceeds 1mm, you will encounter a situation where the locking points can reach but cannot lock tightly.
- Check the engagement depth of the locking points. After closing the sash, the locking points should engage into the locking blocks by 2-3mm.Inspection method: apply a small mark on the locking block (pencil graphite is sufficient), close and then open the window, and check whether the engagement marks are even.If only the edge is rubbed, it indicates insufficient engagement and poor locking;If the engagement is too deep, the handle becomes difficult to turn, and long-term use will accelerate wear.
Key trade-off: The goal of hardware adjustment is not "the tighter, the better," but "uniformity." Only when the four corners of the sash receive equal force can the weatherstripping compress evenly. If you only focus on tightening the locking points, it often leads to one-sided stress on the sash, which over time causes sagging.
Glass installation and glazing bead fixing: key points for installing insulated glass
The FG110F reference configuration uses 5+27A+5 insulated glass. Pay attention to three points during installation:
- The position of the glass setting blocks must be accurate. Place the load-bearing setting blocks at the quarter points of the sash bottom (not the center), and the side setting blocks on both sides of the glass.If the setting blocks are misplaced, the weight of the glass will be transferred through the glazing bead to the sash frame, causing the sash to deform and sag.
- The installation sequence of the glazing beads is important. Install the short-side glazing beads first, then the long-side ones, and finally tap them lightly into place with a rubber mallet.The joints of the glazing beads should be left at the top or sides of the sash, not at the bottom—the bottom is the drainage and load-bearing area, and leaving joints there can easily cause water ingress or loosening.
- Seal inspection of the insulating glass. Before installation, check whether the butyl sealant on the glass edge is continuous; after installation, check whether the gasket between the glass and the glazing bead is fully seated.If the rubber strip has a break, the hollow layer will gradually let in air and cause fogging, and the thermal insulation performance will decline accordingly.
What causes the sash to sag or fail to lock tightly?
These two issues are most common on the FG110F, and the causes usually fall into three categories:
| Phenomenon | Common Causes | Handling Direction |
| Sash sagging (bottom rubs against the frame when closing) | Hinges not leveled or load-bearing shim position shifted | Re-adjust the page eccentric screw and check the position of the glass setting block. |
| The lock does not close tightly (the handle turns to position but the sash remains loose). | Insufficient engagement between the locking point and the locking plate, or the transmission gear is installed offset. | Adjust the eccentric position of the locking point and confirm that the transmission gear and handle linkage operate normally. |
| The handle becomes increasingly stiff with use. | The locking point engages too deeply, or the sash deforms due to the weight of the glass. | Appropriately reduce the engagement amount and check whether the glazing bead is under uneven stress. |
Judgment and recommendation: If the problem occurs within one week after installation, it is basically a commissioning issue, and readjustment will resolve it;If it occurs after six months of use, first check whether the glass setting blocks have shifted and whether the glazing beads are loose. These two items are the most common hidden hazards after long-term use of inward-opening windows.
Common Questions
Q1: Does the lock point adjustment of the FG110F require special tools? It requires hex wrenches (usually 4mm or 5mm) and a Phillips screwdriver. The eccentric adjustment screws on the lock points and hinges are operated with these tools, and no special equipment is needed.
However, it is recommended that installation personnel familiar with the structure of inward-opening windows perform the adjustment to avoid repeated adjustments that may strip the screws.
Q2: When installing 5+27A+5 insulating glass, what is the fitting allowance between the glass size and the window sash opening? The glass should be 4-6mm smaller than the sash opening on all sides, and this gap is used for placing setting blocks and gaskets. If the gap is too small, the gasket may be squeezed during glass installation, leading to seal failure;If the gap is too large, the glass will shake and produce abnormal noise under high wind pressure.
The specific allowance is subject to the drawings provided by Haipai Sichuang, and there may be slight differences among different series.
Q3: After adjusting the sash sag, it recurs after a period of time. What is the cause? If the sag recurs repeatedly, it is most likely not due to loose hinge screws, but rather the displacement of glass setting blocks or loose glazing beads, which causes the glass's own weight to be transferred to the sash frame. It is necessary to remove the glazing beads to check the position of the setting blocks, rather than repeatedly adjusting the hinges—adjusting the hinges only treats the symptom, while the incorrect position of the setting blocks is the root cause.
Q4: Does the transmission of the double inward-opening window require regular maintenance? It is recommended to apply a small amount of lubricant (lithium-based grease is sufficient) to the transmission rod and locking points every six months. The transmission of the inward-opening window is exposed to the indoor side for a long time, accumulating less dust than the outward-opening window, but when the handle turning force becomes heavier, it is a signal that lubrication is needed. Do not wait until the lock is not closed tightly before dealing with it.
Q5: If the lock point is found to be misaligned with the lock plate during installation, can the lock plate position be adjusted directly? Yes, but note that the adjustable range of the lock plate is usually only 2-3mm. If the deviation exceeds this range, it indicates that the installation position of the transmission is problematic. The transmission should be repositioned rather than forcibly bending the lock plate.
Forcibly adjusting the lock plate will cause uneven force on the lock, and the window sash may deform after long-term use.
Learn more
Installation is the final step in unlocking the full performance of the FG110F double inward-opening thermal break window.If you need to confirm opening dimensions, wall conditions, or fixing solutions during the project preparation phase, you are welcome to submit your drawings and on-site data to the Haipaisichuang team, and we will assist you in matching the most suitable installation solution.
Related products:FG110F double inward-opening thermal break window